Source Media Arcade is the 3D frontend I've been developing for launching movies, emulators, and games (built with the Source engine).
With this latest update, it now has a downloadable add-on content system built-in, which lets you download and install add-ons, such as new cabinet models or emulator definitions, with a single click.
Another noteworthy feature to make it into this update is random item selection. You can now specify if you want a completely random item, OR a random item of a specific TV show, movie series, group, etc.
Download the HL2 mod from: http://www.smarcade.net/download.html
If you do not have a lot of experience with Source engine mods, I recommend you install with Desura.
If you just want to upgrade your 2.0 install to the current version, click here.