More is better, as they say, and this seems to apply to GoPros just as well as pretty much anything else. The Dual HERO System is a waterproof housing that lets you use two of the popular HD actioncams simultaneously. You can set one to record video while the other takes pictures, or have them both take video and convert it to 3D later on with some free software. The included sync cable means you only have to control one interface for both cameras, and the entire thing is waterproof up to 197 feet, or 60 meters. It’s $200.