Nobody reads Terms of Service agreements. You know it, I know it, and the companies that come up with them know it. Even if the stupid ToS box makes you scroll down the whole way before clicking "Accept," who would be crazy enough to wade through all that crap? Answer: ToS;DR, and you'll be glad they did.
ToS;DR is an abbreviation of "Terms of Service; Didn't Read" which is a good description of how most people who aren't lawyers react to a ToS. Maybe, if you're super paranoid, you try and find the clause about whether or not your email address is going to get sold to recently deposed Nigerian princes, but odds are that most of the time you just blindly agree to whatever's in there.
Don't feel bad, that's what everybody does, but because everybody knows that everybody does it, there is sometimes a bunch of nasty stuff hidden in the ToS agreements of otherwise reputable websites. And this is where ToS;DR comes in: they grade ToS agreements on fairness and friendliness, parsing out all the important info in a way that humans can understand.
Here's an example (click to enlarge):
When a service is added to ToS;DR, smart people read through the ToS of that service and identify and comment on potential issues. When a consensus has been established, the ToS is assigned a score based on what's good and what's bad, as presented in those handy charts above. In this example, Twitpic hits rock bottom with the worst possible score ("the terms of service raise very serious concerns"), while Github does pretty well ("the terms of services are fair towards the user but they could be improved").
ToS;DR is just in its infancy, and not a lot of services have received scores yet, although many popular sites are currently under scrutiny. The hope here is that eventually, making ToS agreements transparent and easy to understand will circle back and help influence them to be fairer and more user friendly. In the meantime, while the info you find on ToS;DR may not stop you from signing up for anything, at least you'll be going in knowing a heck of a lot more than you did before.