XFX Radeon HD 4850 1GB DDR3 PCIe graphics card - $40 @ newegg

I know this isn't strictly a game - but you can't play PC games without a graphics card, right?  Newegg has the
XFX Radeon HD 4850 HD-485X-ZNFC Video Card  This is an amazing deal for a mid-level graphics card.  If you bought your current card more than a year ago then this would probably be an upgrade for you.

To get the $40 price tag, click on the above link, then enter the code XFXVC517 at checkout to reduce the price by $40.  You'll then need to send in a $30 mail in rebate form within 30 days, and you'll get another $30 back bringing the final price down to $40 with free shipping. That's one sweet deal!