What sort of fighter do you need? Even at level 7, assuming an average budget of 19K gp (as set forth on DMG 135), you can take a fighter in a number of directions:

-Mounted Combat, Ride-By Attack, Spirited Charge with lance emphasis: Reach, 3x damage on a mounted charge (5x on a crit with mounted charge, making this a rare instance where I would recommend Power Attack for a one-handed weapon), superior land speed for getting to and taking care of hotspots, and max ranks in Ride + a decent Dex mod means a good chance to avoid attacks meant for the mount, which is usually more fragile than the rider at this level. What you want to do with this build is charge in, skewer the foe, then use the rest of your formidable movement and Ride-By Attack to get back out of melee, because lances can't hit adjacent enemies and your mount probably can't hit as often or as hard as you can. As long as your comrades can keep open charging lanes wide enough for your mount, feel free to rinse and repeat as often as required.

-Power Attack, Cleave, Great Cleave with two-handed weapon emphasis: Massive damage per hit, even more so on a critical. Great for minion kill and bashing through low to moderate amounts of DR, and also makes a great stand-in if the barbarian is indisposed. As it turns out, most of the weapons in the PH that fit this build best are slashing, so the Whirling enchantment (in the Magic Item Compendium) isn't a bad option, allowing you to pull off three whirlwind attacks per day with your weapon of choice. Instead of waiting for the perfect moment when you're completely surrounded, however, try using it when you're set upon by more than two enemies, or whenever you're being flanked.

-Combat Expertise, Improved Trip, Combat Reflexes, Exotic Weapon Proficiency (spiked chain): High Str and Dex + decent Int + good BAB progression means that you can yank someone off their feet from 10 feet away, then full attack them while receiving +4 on every swing, then swing at them AGAIN if they try to get up while they're in your expanded threat area; unlike most reach weapons, spiked chains can hit up close as well. Also very good for crowd control, as people will have to give you a wider berth than normal if they want to try to get to the spell-slingers. For best results, use with the cleric's Enlarge Person spell. (Protip: Your reach should technically be 15 feet, not 20, if you're Large and have a reach weapon in this edition. But if your DM thinks otherwise, I see no reason to point this out.)

I could go on, but I don't want to bore you.