Via Hack-a-Day comes this link to a fairly simple and cheap way of adding a wireless remote to your PC. This guy used a US$20 Xbox DVD Kit (basically a remote and an IR receiver), a space USB cable, and the free AutoHotKey program to create a remote for his PC that can execute all sorts of control commands. The receiver can even still be used on your Xbox for movie control. Nifty!
Hardware Beyond the Hype