The USB Filter Wheel by Starlight Xpress:

The Starlight Xpress USB filter wheel is a new product for 2009 and introduces many new features to a useful imaging accessory. It is unique in that it does not require a separate power supply when used with USB control - the high performance DC gear motor runs entirely from the USB supply and consumes less than 100mA. It is also capable of operation from a serial input, or from a switched hand controller, both of which power the wheel from a small dry battery. 

The Starlight Xpress USB filter wheel is light and slim, with an easy change system of thumbscrews to swap filter disks without tools. A variety of threaded adapters is available - T thread, SCT thread and Takahashi 72 mm thread at the moment. The adapters can be swapped by using a small screwdriver to release three stainless screws and lifting off the adapter flange. Each flange can be rotated to any angle before locking down, so that you can orient the wheel and camera into the optimum position. The Starlight Xpress USB filter wheel is quiet in operation and the Hall-Effect 3 bit encoded positioning gives absolute filter locations (not serially sequential) so you can easily swap between any filters without accidentally losing the wheel position. OPT Product Number: SX-SXUFW-2T