Adesso WKB-4200UB keyboard
The keyboard uses 2.4GHz wireless tech with 12 channels that it can change automatically to prevent interference. Wireless range is 30 feet and the keyboard has a small USB receiver. The best feature of the keyboard for the HTPC user is that it has a two-button track pad on the right side rather than a number pad.
That means you can type and control the mouse from one device. Power comes from a pair of AAA batteries and the keyboard has a switch to turn it off when not in use. The WKB-4200UB is available now for a steep $119.99.