I just tried a workout that I pulled out of SELF magazine. It's the first time I've actually ripped out one of those perforated pages with different exercises on it, and I'm glad I gave it a try.
This workout focused on your mid-section, but instead of crunches it was all standing exercises. You can check it out here, and even watch a few videos to learn how to do them.
I really liked each one of these different moves, and they were a lot more comfortable than crunches. I can already feel it in my upper abs, especially, but I don't feel like my neck is out of whack like I sometimes do after do floor ab work. So this was a good workout to clip out - I'll keep doing it!