It's always driven me a bit nuts that the "random" button in Attract Mode doesn't actually run the ROM, it just chooses it. Maybe there should be a second "random" control to choose and then run it?
Anyway, in the meantime, I made a plugin to choose *and* run the ROM. Whoo hoo! Loving having it choose all these crappy old games for me, ha.
EDIT: attaching the updated version here, this should work on all platforms. The rest of the thread is about the old version, before rand0m helped fix it and made it cross platform.
To use, put this plugin in Attract Mode's plugin folder, then go to AM's Controls menu and assign whatever key you'd like to "custom2", which is what the plugin listens for. You can edit the plugin to change that.