Aiming your helmet camera and replaying footage is a problem on most models. The HD170makes it easy, but then hits you with a lot of bulk. Contour is working on a viewfinder app for iOS and Android devices that will wirelessly stream video, but that's not out yet. GoPro's LCD BacPac, on the other hand, is shipping today. We spent a little quality time with one at CES, a tiny screen that clips on the back of a 1080p HD Hero and lets you see what's being filmed and also play back what you've captured earlier. As you can see it adds about a quarter-inch of depth onto the camera but comes with a replacement back door to retain compatibility with all mounts. It's shipping now for $80, making it a somewhat expensive accessory for a $300 camera.