Well, Monsta is correct in that the rectus abdominus runs from point Y to point Y, but don't forget there are many more muscles in the abdominal group that do contribute to the overall appearance/function of the abdominal region. Don't forget about the
hip flexors- when developed they help give you that defined "V" shape down in front.... I hear the ladies really like that....
Reverse crunches
Twisting reverse crunches
Leg raises
Frog kick crunches
Roman chair exercises
There are a bunch more, check out Exrx.com (dot net?) and you'll find some more I haven't listed. Change your exercises regularly, and/or change the order in which you do them to keep the results coming.
Tuna