Hahaha we were talking about that one that you sit on and turn back and forth the other day in class!
They sent it to UHCL, where I go to school, to one of my proffs to test it out. After a few test tries it was clear that there was no benifit so he sent it back to the guy. Well appartently they put in the commercial for it that it was tested at University of Houston Clear Lake, which it was, but what they dont tell you is that he found out it was junk! LOL!
I think it is safe to say that all that stuff is junk and most of is has been proven that it is. I am getting my degree in the heath and human performance field and I am doing an internship as a fit tech in NASA's gym and I am always getting ladys that ask me to show them how to use the ab machines. We only have a few so I show them and ask them how they feel about them and they are usually like ummm..ok. Then I ask them for 5 min of their time to show them a special piece of ab equipment that I love to use and know is the best..........THE FLOOR! Yep after about 3 min they are convienced. :)
Get an incline bench from a local athletic store, or hell, even Wal-Mart. They cost less than 50 dollars, and you can do a lot of exercises on them.
The sit-up is a lot more intense and concentrates all of your upper body weight on your stomach muscles.
Also, a good bench will have a way for you to work on your lower back, too! Don't just focus on your stomach... train the opposite muscle group too, or you're asking for an injury.