The Hercules Tunes Explorer Wireless is yet another USB wireless iTunes remote control, but with a twist. It integrates a small back-lit LCD screen which "displays the song titles, play lists etc" and so allows you to "select your music without having to go to your computer." It has a side mounted thumbwheel for scrolling and since the device is RF and not infra red it is not limited to line of sight. I can imagine this could be a very handy little device for controlling your den computer from the bedroom, for example (provided of course that it's compatible with the Airport Express).
The Hercules Tunes Explorer Wireless is €49.99 (~$65) and is PC as well as Mac compatible.