Yes, you can win real money on PokerStars.net. It's not easy, you must place in a Freeroll, that takes u to a weekly round 2 tournament. In the round 2 tourney there are alot more players and you have to place once again. If you do then you can recieve real money.
I fear that there is no such site where you can bet free money and get real money after winning. But on deposit or after sign up, casinos http://www.casinoscorner.com/ do offer a good sign up or other bonuses. You can also opt to play freeroll as well.