It isn't an exactly what you're asking but in terms of giving away software and still making money on it with games - there are some people making money with fr

It isn't an exactly what you're asking but in terms of giving away software and still making money on it with games - there are some people making money with free flash games. If I remember right the desktop tower defense guys made a little under 100k in a year and I read an article not long ago which suggested the ninja kiwi games website was making something near $30k/mo. Or how about the farmville / zinga games offers where people do certain trial offers to get points in the game? These seem like reasonable answers to your question (though these aren't open source they are still free to play).