The OnLive service which renders console and PC games in the cloud and then streams them to your PC or Mac has gone live today. And you can get the first year of OnLive membership for free.
Note that what you're getting for free is the OnLive membership—which is normally $4.95/month—and not the games. Prices for those will vary, but here are some of the titles you can look forward to:
Assassin's Creed 2, Prince of Persia: The Forgotten Sands and Tom Clancy's Splinter Cell: Conviction from Ubisoft; Mass Effect 2 and Dragon Age: Origins from Electronic Arts; Batman: Arkham Asylum and Just Cause 2 from Square Enix; Borderlands, NBA 2K10 and MLB 2K10 from Take Two; Red Faction: Guerilla from THQ; Fear 2: Project Origin from Warner Bros. Interactive Games; and DiRT 2 from Codemasters along with other great games from publishers, both large and small, representing a wide range of genres.