GoPro just announced a rather enticing addition to its action camera series. The Hero 3 Black Edition is the new flagship model and boasts 4K (4096x2160) recording capability at 12 fps - for $400.
Sure, it is just a helmet camera, but if you are currently looking for a 4K video camera, you are typically looking for a professional camera at a price tag of $5,000 and up. The Black Edition camera can also record at 2.7K, 1440p/48 fps, 1080p/60 fps, 720p/120 fps, and 848x480/240 fps - and run in simultaneous video/photo mode with a 12 MP still camera. It comes with integrated Wi-Fi, support for microSD cards up to 64 GB, as well as a remote.
If you don't need the 4K capability, GoPro also offers a 1080p/30 fps camera with a 11 MP still camera for $300, as well as a 1080p/30 fps model with a 5 MP still camera.