Currently, I can do the following (Including hybrids):
NES
Gameboy (Pre-Advance)
Megaman X1
Megaman X2/3 (Different from X1)
Chrono Trigger
Final Fantasy 4
Final Fantasy 5
Kirby's Dream Land 3
Secret of Mana
Super Bomberman
Super Mario Kart
Super Mario World
Zelda 3 (Link to the Past)
OPL 3 FM
FM Regression
Tohou 6, 7, and 8
Pokemon Fire Red / Leaf Green / Sapphire / Emerald / Ruby
Pokemon Heart Gold / Soul Silver
Pokemon Diamond / Pearl / Platinum
Pokemon Black / White
Pokemon Stadium 1/2
Final Fantasy 8 demo
Zelda Ocarina of Time
Golden Sun: The Lost Age
Full Modern (See: Real instruments)
F-Zero (Don't know where it would fit)
GXSCC (And I don't mean the program, thank you very much.)
Nokia 30 (Don't know where it would fit)
Doom (Don't know where it would fit)
Everything I make is free to download, free to use, just as long as nobody claims they made it instead of me. That'd just be cruel. I also take requests! Though I can't do everything and I generally only release something if it sounds very good to me. anyway. I'm going to list all my creations below, along with three links to various different places you can listen to the same thing at. I don't know why. Why not? Maybe someone has trouble viewing them at one place. They're in order from oldest to newest. I've made a lot more than these, but never released them.
X vs Zero (Megaman X5) - Done in 16 bit with Megaman X1-3 instruments
http://www.youtube.com/watch?v=LCvA2oiwk84 - Youtube (Set quality to 480p for best results)
http://www.sheezyart.com/art/view/2374627/ - SheezyArt
http://chaoticmarin.deviantart.com/art/X-vs-Zero-SNES-remix-196819629 - DeviantArt
http://www.newgrounds.com/audio/listen/406351 - Newgrounds (Higher Quality!) (Recommended)
http://www.mediafire.com/?d9z9z5fe2insogc - MP3 Download @ Mediafire
Pallida Mors (Megaman ZX) - Done in 8 bit
http://www.youtube.com/watch?v=L64Fti5Fqb4 - Youtube (Set quality to 480p for best results)
http://www.sheezyart.com/art/view/2374628/ - SheezyArt
http://chaoticmarin.deviantart.com/art/Pallida-Mors-8-bit-196857799 - DeviantArt
http://www.newgrounds.com/audio/listen/406365 - Newgrounds (Higher Quality!)
http://www.mediafire.com/?1afpyhks5e6pea6 - MP3 Download @ Mediafire
Ganondorf Battle (Zelda: Wind Waker) - Done in 16 bit with Megaman X1-3 instruments
http://www.youtube.com/watch?v=X5HwfI3b76A - Youtube (Set quality to 480p for best results)
http://www.sheezyart.com/art/view/2374629/ - SheezyArt
http://chaoticmarin.deviantart.com/art/Ganondorf-Battle-WW-SNES-remix-197384143 - DeviantArt
http://www.newgrounds.com/audio/listen/409462 - Newgrounds (Recommended)
http://www.mediafire.com/?ov5bnros7cvurud - MP3 Download @ Mediafire
Quint's Theme (Megaman II) - Done in 16 bit with Megaman X1-3 instruments
http://www.youtube.com/watch?v=sr7kCutT_AU - Youtube (Set quality to 480p for best results)
http://www.sheezyart.com/art/view/2374630/ - SheezyArt
http://chaoticmarin.deviantart.com/art/Quint-s-Theme-16-bit-197387249 - DeviantArt
http://www.newgrounds.com/audio/listen/407061 - Newgrounds (Recommended)
http://www.mediafire.com/?y4czavc5aa66dwi - MP3 Download @ Mediafire
Supreme Ruler (Megaman Zero 2) - Done in modern bit with Tohou 6-8 instruments
http://www.youtube.com/watch?v=29FLZFhm1_Q - Youtube (Set quality to 480p for best results)
http://sheezyart.com/art/view/2375759/ - SheezyArt
http://chaoticmarin.deviantart.com/art/Supreme-Ruler-Tohou-Remix-197914368 - DeviantArt
http://www.newgrounds.com/audio/listen/407063 - Newgrounds (Recommended)
http://www.mediafire.com/?jm0z1mc1i0by7cd - MP3 Download @ Mediafire
Grunty's Lair (Banjo Kazooie) - Done in 8 bit
http://www.youtube.com/watch?v=3zyJIg-lB_k - Youtube (Set quality to 480p for best results)
http://www.sheezyart.com/art/view/2375794/ - SheezyArt
http://chaoticmarin.deviantart.com/art/Grunty-s-Lair-8-bit-197932986 - DeviantArt
http://www.newgrounds.com/audio/listen/407292 - Newgrounds (Recommended)
http://www.mediafire.com/?xc54bvg96bciiyf - MP3 Download @ Mediafire
Dark Hollow (Spyro the Dragon) - Done in 8 bit
http://www.youtube.com/watch?v=AXS-3NJ_gFA - Youtube (Set quality to 480p for best results)
http://www.sheezyart.com/art/view/2375974/ - SheezyArt
http://chaoticmarin.deviantart.com/art/FFLIII-Final-Battle-16-bit-198066025 - DeviantArt
http://www.newgrounds.com/audio/listen/407294 - Newgrounds (Recommended)
http://www.mediafire.com/?qax65ep0qvbv8fl - MP3 Download @ Mediafire
Final Boss (Final Fantasy Legend III) - Done in 16bit with Megaman X1-3 instruments
http://www.youtube.com/watch?v=TSQuCO6jCvY - Youtube (Set quality to 480p for best results)
http://sheezyart.com/art/view/2375987/ - SheezyArt
http://chaoticmarin.deviantart.com/art/FFLIII-Final-Battle-16-bit-198066025 - DeviantArt
http://www.newgrounds.com/audio/listen/407627 - Newgrounds (Improved version!) (Recommended)
http://www.mediafire.com/?8px989ixoa0xxsf - MP3 Download @ Mediafire
Skull Fortress 3 (Megaman 3) - Done in modern bit with Tohou 6-8 instruments
http://www.youtube.com/watch?v=T64ejkr_wpY - Youtube (Set quality to 480p for best results)
http://www.sheezyart.com/art/view/2377706/ - SheezyArt
http://chaoticmarin.deviantart.com/art/MM3-Skull-Fortress-3-Tohou-198869981 - DeviantArt
http://www.newgrounds.com/audio/listen/407628 - Newgrounds (Recommended)
http://www.mediafire.com/?9a5p3j9a5hzudi7 - MP3 Download @ Mediafire
Pokey Means Business (Earthbound / Mother 2) - Done in modern bit with Tohou 6-8 instruments
http://www.youtube.com/watch?v=_CQrhdjR3WQ - Youtube (Set quality to 480p for best results)
http://www.sheezyart.com/art/view/2378514/ - SheezyArt
http://chaoticmarin.deviantart.com/art/Pokey-Means-Business-Tohou-199290127 - DeviantArt
http://www.newgrounds.com/audio/listen/404278 - Newgrounds (Recommended)
http://www.mediafire.com/?e6ztx7a47z9zk14 - MP3 Download @ Mediafire
Gary Battle (Pokemon Fire Red / Leaf Green) - Done in modern bit with Pokemon Heart Gold / Soul Silver instruments
http://www.youtube.com/watch?v=_o3ZtR2-fRA - Youtube (Set quality to 480p for best results)
http://sheezyart.com/art/view/2378517/ - SheezyArt
http://chaoticmarin.deviantart.com/art/Gary-Battle-HGSS-remix-199292304 - DeviantArt
http://www.newgrounds.com/audio/listen/408183 - Newgrounds (Recommended)
http://www.mediafire.com/?g5250fds8a12g4q - MP3 Download @ Mediafire
"A" (Tetris [Gameboy]) - Done in 16bit with Megaman X1-3 instruments
http://www.youtube.com/watch?v=dLIix21BnK8 - Youtube (Set quality to 480p for best reslts)
http://sheezyart.com/art/view/2378524/ - SheezyArt
http://chaoticmarin.deviantart.com/art/Tetris-A-16bit-remix-199294733 - DeviantArt
http://www.newgrounds.com/audio/listen/408184 - Newgrounds (Recommended)
http://www.mediafire.com/?4bn33767n64l56r - MP3 Download @ Mediafire
Beast Masters World (Spyro the Dragon) - Done in 8bit
http://www.youtube.com/watch?v=hVUIjRDy7sc - Youtube (Set quality to 480p for best results)
http://www.sheezyart.com/art/view/2380237/ - SheezyArt
http://chaoticmarin.deviantart.com/art/Spyro-Beast-Masters-8-bit-200049461 - DeviantArt
http://www.newgrounds.com/audio/listen/408953 - Newgrounds (Recommended)
http://www.mediafire.com/?56hsgzroh50rss5 - MP3 Download @ Mediafire
Ending Theme (Spyro the Dragon) - Done in 8bit
http://www.youtube.com/watch?v=ufj6nn-wGVs - Youtube (Set quality to 480p for best results)
http://sheezyart.com/art/view/2380239/ - SheezyArt
http://chaoticmarin.deviantart.com/art/Spyro-Ending-8-bit-200050643 - DeviantArt
http://www.newgrounds.com/audio/listen/408954 - Newgrounds (Recommended)
http://www.mediafire.com/?xkd1e9ulj793d6a - MP3 Download @ Mediafire
Quint's Theme (Megaman II) - Done in FM Synth
http://www.youtube.com/watch?v=JBNyDUeJpL8 - Youtube (Set quality to 480p for best results)
http://sheezyart.com/art/view/2385305/ - SheezyArt
http://chaoticmarin.deviantart.com/art/Quint-FM-Synth-Arrangement-202584764 - Deviantart
http://www.newgrounds.com/audio/listen/409463 - Newgrounds (Recommended)
http://www.mediafire.com/?ccyv9714k9d64s3 - MP3 Download @ Mediafire
"Equated Captives" - N's Theme (Pokemon Black/White) - Done in 8bit
http://www.youtube.com/watch?v=XwqG4A4Gb3E - Youtube (Set quality to 480p for best results)
http://www.sheezyart.com/art/view/2386987/ - SheezyArt
DeviantArt version currently unavailable due to a bug in the tool I use to convert the MP3s into flash files.
http://www.newgrounds.com/audio/listen/410748 - Newgrounds (Recommended)
http://www.mediafire.com/?8m48ov8cudne8ou - MP3 Download @ Mediafire
Final Battle with N (Pokemon Black/White) - Done in 8bit
http://www.youtube.com/watch?v=sdb7QLoGgVo - Youtube (Set quality to 480p for best results)
http://www.sheezyart.com/art/view/2386991/ -SheezyArt
http://chaoticmarin.deviantart.com/art/Final-Battle-N-8-bit-203269324 - DeviantArt
http://www.newgrounds.com/audio/listen/410751 - Newgrounds (Recommended)
http://www.mediafire.com/?eulwc1dmy1szqep - MP3 Download @ Mediafire
Genesis Prototype - Active (By Tsukihana) - Done in 8bit
http://www.youtube.com/watch?v=a4LJ5qD8yco - Youtube (Set quality to 480p for best results)
http://www.sheezyart.com/art/view/2388577/ - SheezyArt
http://chaoticmarin.deviantart.com/art/Genesis-Prototype-8-bit-204025229 - DeviantArt
http://www.newgrounds.com/audio/listen/412031 - Newgrounds (Recommended)
http://www.mediafire.com/?cpm62h334ibob9d - MP3 Download @ Mediafire
X vs Zero (Megaman X5) - Done in 16bit with Megaman X1/2/3 instruments.
http://www.youtube.com/watch?v=K6rEL3o9dy8 - Youtube (Set quality to 480p for best results)
http://sheezyart.com/art/view/2393604/ - SheezyArt
http://chaoticmarin.deviantart.com/art/X-vs-Zero-SNES-remix-V2-205593343 - DeviantArt
http://www.newgrounds.com/audio/listen/414867 - Newgrounds (Recommended)
http://www.mediafire.com/?61hdu5mj5yg72ut - MP3 Download @ Mediafire
Title theme (Spyro the Dragon) - Done in 8bit
http://www.youtube.com/watch?v=VwKybqINV-Y - Youtube (Set quality to 480p for best results)
http://sheezyart.com/art/view/2393613/ - SheezyArt
http://chaoticmarin.deviantart.com/art/Spyro-Title-Theme-8-bit-205596245 - DeviantArt
http://www.newgrounds.com/audio/listen/414874 - Newgrounds (Recommended)
http://www.mediafire.com/?cicby836o8jvcd5 - MP3 Download @ Mediafire
Final of Puyo Puyo (Dr. Robotnik's Mean Bean Machine) - Done in 8bit
http://www.youtube.com/watch?v=b_x9O9IYZAc - Youtube (Set quality to 480p for best results)
http://sheezyart.com/art/view/2415729/ - SheezyArt
http://chaoticmarin.deviantart.com/art/Final-of-Puyo-Puyo-8-bit-209952840 - DeviantArt
http://www.newgrounds.com/audio/listen/422186 - Newgrounds (Recommended)
http://www.mediafire.com/?kxxb5j0drzpw68c - MP3 Download @ Mediafire
Battle! Cynthia (Pokemon Diamond / Pearl / Pleatinum / Black / White) - Done in 8bit
http://www.youtube.com/watch?v=3YgWUx35q9s - Youtube (Set quality to 480p for best results)
http://sheezyart.com/art/view/2417278/ - SheezyArt
http://chaoticmarin.deviantart.com/art/Cynthia-Battle-8-bit-210980879 - DeviantArt
http://www.newgrounds.com/audio/listen/423745 - Newgrounds (Recommended)
http://www.mediafire.com/?i2u3flx37q110b2 - MP3 Download @ Mediafire
Von Bolt's Theme (Advance Wars Dual Strike) - Done in Modern Bit with Tohou 6, 7, and 8 instruments
http://www.youtube.com/watch?v=rkj_g01vs8A - Youtube (Set quality to 480p for best results)
http://www.newgrounds.com/audio/listen/426070 - Newgrounds (Recommended)
http://www.mediafire.com/?41i8uncyxt1917u - MP3 Download @ Mediafire
Grabbag (Duke Nukem 3D) - Done in FM Synth
http://www.youtube.com/watch?v=4ssAzVQHqDM - Youtube (Set quality to 480p for best results)
http://www.newgrounds.com/audio/listen/428095 - Newgrounds (Recommended)
http://www.mediafire.com/?5us2dqscbtaie42 - MP3 Download @ Mediafire
Sol Sanctum (Golden Sun) - Done in Modern Bit using Pokemon R/S/E instruments
http://www.youtube.com/watch?v=9jTh1PTNfDc - Youtube (Set quality to 480p for best results)
http://www.newgrounds.com/audio/listen/431333 - Newgrounds (Recommended)
http://www.mediafire.com/?6v6oc4b01b1o7za - MP3 Download @ Mediafire
Battle! Lance (Pokemon Heart Gold / Soul Silver) - Done in 8 bit
http://www.youtube.com/watch?v=W-gHQT-BiAw - Youtube (Set quality to 480p for best results)
http://www.newgrounds.com/audio/listen/431838 - Newgrounds (Recommended)
http://www.mediafire.com/download.php?0avoc902kmec700 - MP3 Download @ Mediafire
Battle! Rival (Pokemon Ruby / Sapphire / Emerald) - Done in Modern Bit using Tohou 6, 7, and 8 instruments
http://www.youtube.com/watch?v=MymmkmFChLA - Youtube (Set quality to 480p for best results)
http://www.newgrounds.com/audio/listen/434144 - Newgrounds (Recommended)
http://www.mediafire.com/?dma24ge6fkmw2fw - MP3 Download @ Mediafire
Battle! Champion (Pokemon Ruby / Sapphire / Emerald) - Done in 8 bit
http://www.youtube.com/watch?v=DmiPj3d_8nY - Youtube (Set quality to 480p for best results)
http://www.newgrounds.com/audio/listen/435973 - Newgrounds (Recommended)
http://www.mediafire.com/?e9gj2w0igzm9fy2 - MP3 Download @ Mediafire
Ikana Castle (Legend of Zelda: Majora's Mask) - Done in 8 bit
http://www.youtube.com/watch?v=E_TYqZ-RvfI - Youtube (Set quality to 480p for best results)
http://www.newgrounds.com/audio/listen/442121 - Newgrounds (Recommended)
http://www.mediafire.com/?9oi5nkapskjj57n - MP3 Download @ Mediafire
Battle! Cynthia V2 (Pokemon Diamond / Pearl / Platinum) - Done in 8 bit
http://www.youtube.com/watch?v=esP5AVj13Rw - Youtube (Set quality to 480p for best results)
http://www.newgrounds.com/audio/listen/442878 - Newgrounds (Recommended)
http://www.mediafire.com/?idj0us6l7suxz6r - MP3 Download @ Mediafire
Battle! Gary (Pokemon Fire Red / Leaf Green) - Done in 8 bit
http://www.youtube.com/watch?v=qAv9fMWuyZY - Youtube (Set quality to 480p for best results)
http://www.newgrounds.com/audio/listen/451577 - Newgrounds (Recommended)
http://www.mediafire.com/?x7z7rb3sle4xqgg - MP3 Download @ Mediafire
Sigma 2nd Battle (Megaman X6) - Done in 8 bit
http://www.youtube.com/watch?v=Io53cVHtULk - Youtube (Set quality to 480p for best results)
http://www.newgrounds.com/audio/listen/454918 - Newgrounds (Recommended)
http://www.mediafire.com/?76cl2g8xzugtzs4 - MP3 Download @ Mediafire
Battle! Gary (Pokemon Fire Red / Leaf Green) - Done in Modern Bit with Pokemon Black / White instruments
http://www.youtube.com/watch?v=xBgIFpY85G8 - Youtube (Set quality to 480p for best results)
http://www.newgrounds.com/audio/listen/455900 - Newgrounds (Recommended)
http://www.mediafire.com/?w44mb4daumgodze - MP3 Download @ Mediafire