Dragonvale! Honestly, its kind of lame. But I mean, its a great game if you like going in once every few hours, getting cash, and breeding dragons. The thing that impresses me most is that they constantly update the game. Even today they just released a Clover dragon for St.Patricks day, and a few days ago it was the Leap Year dragon.
Oh, and the best part, if you don't mind being patient, free as free can be!