When I actually do my ab routine (

I swear I'll work out more this fall), I do a lot of different types of crunches in sets of ten or twenty so that I don't get too bored. Here are some that I do, if I can remember:
1. Normal crunches and situps...I figure that you can figure those out on your own

2. Lie on your back and put one hand behind your head. Bend your knees and twist so that your back stays flat and your legs lay to the side. Then do crunches in that position. When you finish one side, switch to the other side and repeat.
3. Lie on your back and put your hands under your hips/butt (wherever you need the support). Then raise your legs. Hold them 6 inches above the ground (the time is up to you--as long as you can stand it?)
4. Variation of #3. The position is the same, but the action is different. Bend your knees and raise your legs up. Straighten them and v.e.r.y slowly lower them to just above the ground. Without touching the ground with your feet, repeat the motion.
5. Variation of #3. Same position, but when you raise your feet, do scissor-kicks (cross your legs and open them over and over). I'm not sure I know how to explain this.
6. Squat-thrusts! Jump up as high as you can (reach with your arms), then bend your knees so that you are squatting and put your hands on the floor outside of your knees. Jump back as far as you can with your legs (full extention--pushup position) and then jump back to the squatting position. It's important that you jump--don't walk yourself back slowly. The whole thing should sort of run together with no pause between the initial jump and the squat. When you get back to the squat, jump up as high as you can again and continue. THis also works other muscles like your legs, but especially if you really stretch it can really make your abs burn the next day.
7. Lie on your back and put your hands behind your head. Raise your legs off of the floor and bend one of them so that the knee is pointing toward you. Sit up toward the knee, leading with the opposite arm. Alternate between your two legs without letting them touch the ground. I don't think I've explained this well...hey, I thought of an example. If you've seen Zoolander, think of the scene with Derek in his shared apartment right before they go out and his friends blow themselves up. In that scene, one of the male models in the apartment is doing cool-looking crunches that are basically what I'm describing. I hope that helps.
Uggh, that's all I can think of (or that I want to type) for now. I know that there are others. If you do one set of ten of each of those (don't breal between sets), that's 70 right there and none of them had time to get boring. You can repeat it as many times as you want/can. You might also add in three more types so that you get an even 100 after doing each once (I like doing even numbers of them). You can also use a balancing ball thing for crunches, or lift a 10-pound energy ball above your head while you crunch.
Does anyone else have any suggestions?