....bicycles with upper body motion
lying leg scissors
standing/kneling pulley curnches
incline sit-up with a medicine ball being thrown at odd angles.....high low and to the sides...
swiss ball crunches
My abs are under tight scrutiny by my chiro right now as I get my back in order but the work conssits of lots of lying crunches, and various stuff like what Shadow mentioned.
I don't do very much...I have a very flat stomach naturally. If I scrounch I have a definite 4 pack....more definition will come from diet for me more than training.
I do 3 X8 weighted crunches 80-100 lbs
roman chair raises 3 X 15
While training for Pl'ing I did alot of weighted and band work for my abs. My favorite is to lie on a bench .. wrap a band around your ankles and have someone holding it for resistance standing about 4 feet from you.. the further away the more resistance. Hold on to the top or sides (I hold the top) of the bench and pull your legs in.. in a reverse crunch motion.. KILLER
I do weighted crunches with a rope, leg raises and stability ball work.
There are lots of ab ideas in the Spring 2005 Oxygen mag. The title is "Abs training for woman" - like the issue thay had for glutes last year, but it's abs this year.
I can try to scan a few of the pages if anyone wants to have a look.