My favorite game site is World Winner. I joined through Inbox, but you can also join directly or thru MyPoints. When i joined I received a bonus of game credits equal to my initial deposit ($20).
They do not pay you to play, but you can compete against other members for cash (if you have game credits, half the tournament charge comes from the game credit and half from your real money.)
I don't compete often -- usually I play warm-up games and challenge game with no money involved. But periodically, I take a risk with games I'm good at and try a couple of tournments. I've been reasonably lucky and am still ahead of the game. But this is not a source of "earnings", it just for fun.
WW does have daily Free tournament were you can earn reward points that in turn can be converted in to game credits. Plus they have special tourniments and gimmicks to let you earn more rewards points.
One thing I like about WW is that there are no ads (other than their own) on the site. They make money by collecting an admin fee on every cash tourniment (30%)
The other game site that I have used is IWON.
This site has lots of games, and they "pay" you with coins that you can use to enter sweepstakes. I've found that you have a reasonable chance of winning the daily sweepstakes if you drop 100 million in coin in the sweeps for the $100 prize. Never tried for the weekly, monthly or annual sweeps.
You can earn a maximum of 2 million coins a day -- which would generally take me 3-5 hrs of playing (I have dial-up and a slow PC).
Unfortunately, this site is overloaded with ads (that's how they pay for the sweeps winnings). And the ads slow everything down.
It does have an interesting twist to keep you coming back -- with their Team Charity competition. Members can join a Charity team (there are hundreds on the site - both national and member created) and the top 3 coin earning Teams earn real dollars for their charity. Your Team is also a source of information and social interaction.