I mentioned PlayDeb, from the GetDeb guys, as being something to be really excited about with the upcoming release of Ubuntu 9.10 Karmic Koala. I just checked out the site and their new beta is finally up and running! They currently are only serving Jaunty (which is fine since Karmic is only in alpha) but Karmic support is sure to come.
The new site was designed by the Nexuiz Nijnaz, players of the great cross-platform FLOSS game, Nexuiz. I am a bit disappointed seeing copyright retained on the site instead of using a free culture friendly license like the Creative Commons Attribution-Share Alike license, but it looks like this is just what both the Nexuiz and GetDeb guys do on all their websites and i certainly won't make a big deal about that. The website is wonderful, and they've done a great job. The "Updates" page lists all the available games and allows you to filter them by genre, and install them by simply clicking on an apt:// link.
Each game has a description and screenshot, and many even have videos attached! You can register to rate and comment on games, and if you like PlayDeb, i encourage you to use the donate button on their "About Us" page.
In related news: The Ubuntu Gaming Team just had our first meeting which was very successful and i'll be posting all the details soon!