Jiu-Jitsu Pull-ups
My cousin's always been ragging on me about increasing my core strength, and then I discovered this workout:
Tried some of it yesterday. Was FAR from perfect, but sitting up in bed this morning brought a tear to my eye, and not the happy kind. Hahaha.
Fitness geeks and gym rats (i.e. Janine and Cat, respectively :p ) among you may want to try it out for your back and abs.