I will now echo Tombuntu's echo about an Ubuntu repository for games. Isn't that neat?
Playdeb includes an APT software repository, and a games list that can be used to install games simply by clicking an install link. The repository can be easily added by installing a DEB package. The install links in the games list require AptURL, which is standard in Ubuntu since 7.10, but Playdeb requires an updated version to be installed. A DEB package for this is also provided.