Just in case anyone is looking for or wants more detailed info or learn more on the 12v world. The12volt.com
Car Alarm, Car Stereo, Mobile Video, and Cruise Control Info for Installers is an excellent link to all things 12v. It's heavily geared toward the automotive and car stereo world but the fancy and complicated projects they do there are awesome.
I found it a few years ago researching a project I was working on. If you're looking for a new project...definitely check it out.