Normally, I wouldn’t highlight a product from Woot due to the time-sensitive nature of their offerings, but this could be useful for quite a few mobile tech users out there. Woot currently has the Gyration Ultra Compact Keyboard Suite for $29.99 plus shipping. The package includes a compact keyboard and mouse; it looks like the wireless usage is via RF, so I’d guess there is a USB receiver. The mouse has a gyroscope in it for "off the desktop" use as well.
Note that this product is a refurb; that might not scare you away, but it’s worth a mention. This could be a nice, inexpensive addition to a UMPC or other mobile computing device at this price. Happy shopping!