The Flip Bracket Right Angle Bracket Adapter from ClickSnap changes the camera angle by 90°. It features two 1/4" holes, as well as a 1/4"-20 stud to tighten down the camera. It can be used in conjunction with 1/4"-20-based camera mounting hardware such as tripods and monopods as a simple way to flip the camera 90°.
The Flip Bracket is also compatible with ClickSnap's ProPole, an adapter that converts the end of a painter's pole into a 1/4"-20 stud. In addition, it will accept the ProMount, another ClickSnap product, which convents the GoPro's proprietary "shoe" mount into a standard 1/4"-20 female.