Some of them are really quite a farse- they want your credit card information. Some want you to be a member for so long. Some want you to refer "x" number of people. You'd think that we'd refer people if we were given a chance to test their freerolls to begin with.
There's only 1 can brag about. That's at Royal Vegas. The hitch with it though is that if you win anything, before you can withdraw, you have to have so many raked hands and deposit at least once or you forfeit all.
That's my 2 cents on no deposit sites offering bonus bucks.