Free to register, but costs every time someone clicks an ad.
Yes, there are plenty of people who make money using it (I'm one of them).
I know atleast 30 different guys who are making over $10,000 a day (and can be verified by 3rd party sources).
It just takes ALOT of time, and will definately take some out of pocket expenses to get going.
Google Money System Revealed
Who Is The Richest Man In The World - I AM