Does it really work to get you out of a contract?
I would stick with the two main ones that allow you to trade your contract with other people they are
They were both mention in this New York times Article. http://www.nytimes.com/2007/03/10/technology/10mon…
If I want accurate information I go to a library. After all a books take a lot more time and more money then web sites and almost anyone can have a web site up within hours some say minutes.