Linux Game Repository With a GUI: DJL
Djl is an open-source (GPL licensed) game manager written in Python 2.5 for the GNU/Linux Operating Systems, inspired by Valve's Steam software for Windows for which anyone can submit games.
The application is an interface to a repository which is continuously updated, and has lots of games. Basically, it's kind of like a PlayDeb with a GUI (please note that it does not use the PlayDeb repository, in fact it has nothing to do with it, I just gave it as an example). Djl displays information about the games in it's repository, screenshots and it also allows you to install the games with a simple click.