Crunches. I know people say you can't spot reduce - and they are probably right - maybe I just loose weight from my stomach more quickly than other areas, but do crunches; stick your toes under something like a chest of drawers/wardrobe/something low to the ground (for leverage so you don't bounce around!) and then cross your arms on your chest, bend your knees and bring your ass as close to the wardrobe/draws as you can, then lie on your back and pull yourself up to face whatever you are facing, making sure you don't let your arms get loose and move position (this is the tricky part after like 70 or so crunches!).
Other than that do lots of other exercise, cut down on the high fat foods and drink gallons of water (trickier than it sounds!)