Trackmania is a racing game, and has been released for some time.
http://www.trackmanianations.com/indexUk.php
It's graphics are approximately Xbox quality, and it's not a particularly serious simulation. Those aren't the selling points.
The selling point is that the game has highly customizable games and tracks, and you can trade those tracks and games over the web for free. Just put them up on the site. It has a ton of track customization options, including items and background and track style (dirt, asphalt, etc).
This effectively means this game has -- for free -- an unlimited number of tracks and cars. I think it's an awesome idea, even though I'm not a racing fan.
http://i14.photobucket.com/albums/a324/Arkives/Disccopy.jpg%5B/IMG%5D">
http://i14.photobucket.com/albums/a324/Arkives/Disccopy.jpg%5B/IMG%5D">
