Tilt Platform - 3/8 "-16 to 1/4 "-20 Mount Adapter - Syrp 1 Year Limited Warranty. Allows you to level your camera when used on a slider set at a angle. Maximum payload of 13.2 lb. Can be easily mounted on top of Genie II Linear using the QR plate for fast and easy setup. Tilting range from 0 Degree up to 180 Degree and accurate adjustment with angle markings up to 90 Degree.
This is a simple device that does only one thing, but very well. It has a quick release lever so you can adjust the angle very quickly on the fly. You can get the same effect by adding a ball head to the camera mount, but you'll be spending about the same amount, and I don't think it'll be as elegant a solution.