It's a small IR remote with 17 keys, nicely laid out. Bottom two keys on photo are Cycle (alt-tab in Windows?) and Menu.
The IR receiver connects via a USB port on your computer or a powered USB hub. There are two models, the older Media Remote and the newer Express Remote. $20 and $30 respectively on Amazon at the moment, including a rebate. Both use the same driver, but the Express receiver can also be plugged into the USB port of an Airport Express with no driver, and it becomes a dedicated iTunes remote.
When not connected via APEx, the button actions can be remapped on a PC or Mac. You can also use a regular IR remote with the receiver, if the remote can control a JVC VCR.