I got this in the mail last week and I must say my XBMC experience on the Pi is 100 times better. They are on ebay for ~$15 shipped and supposedly are compatible with PS3 and Xbox 360 as well. The listing didn't mention raspberry pi at all but I figured I'd take the risk. When I first plugged it in nothing happened, rebooted the Pi and bingo it works perfectly.
If you hate using the on screen keyboard I highly recommend getting one of these, it'll be the best $15 you ever spend :)
I don't want to link to a particular ebay listing since they are only valid for a short time. Instead just search ebay for "wireless handheld keyboard touchpad" and you should see a bunch. Just FYI they come in white too.
For a few dollars more one of my favourite Chinese retailers looks like it sells the same one: