planks, side planks, cable trunk twists, hanging leg raises, stability ball jackknife, stability ball roll out, decline sit ups (not cunches ;p) and believe it or not sprinting will help give you good abs, so maybe trade a cardio day for an intervals day, where you sprint, then walk, then sprint, then walk, in intervals.
Also you have to be around 6-9% body fat I think it is for an entire six pack to show so stick with your free weights and cardio.
It's lack of faith that makes people afraid of meeting challenges, and I believed in myself. ~Muhammad Ali
You must have long-range goals to keep you from being frustrated by short-range failures. ~Charles C. Noble
July 6th 2010: 225 lbs, 24% body fat
Nov 30th 2010: 181 lbs, 12% body fat
Dec 28th 2010: 177 lbs, 11% bf
Total weight loss 48 lbs.