Hi-Rez has put their MMO Global Agenda up for cheap and the best part is all the money goes to help aid the victims of the Japanese Earthquake/Tsunami.
They are charging only $10. The nice thing about this MMO is there’s no monthly fee to play. I’m not sure if there’s in-game items you can buy. I really don’t know too much about the game. You can do a free trial if you want to try it out first.
Looking at the Hi-Rez website it looks like they’re making a new Tribes game! OMG I loved the first game so much.
Apparently if you enter the coupon code GACOU524266055336 after you’ve entered your credit card information, you can get the game for $4.99. If you enter it at the first coupon textbox you will be prevented from buying the game. So do it after you’ve entered your CC info.
Edit: This game is also available on Direct2Drive (D2D) for $9.95 if you prefer to have your games on that service. If you use the 20% off FPS coupon specwar5 the game will only be $7.96. The D2D version comes with a free exclusive in-game item. A cowboy hat and sunglasses. However, I don’t think these purchases would contribute to the relief fund. You might be able to play the game on Steam by downloading the demo version on Steam and then logging in with your account information. YMMV.