The full version of Torrent Droid will be out in a month, but this video shows you what you ned to know already. Scan a UPC bar code and the app will search BitTorrent automatically.
At least one of the major sites (Pirate Bay, Minonova, Demonoid, etc) should return results, and you can then pick a torrent to send to your PC at home to start downloading. The app is a response to the "Android Bounty", which is an initiative from a few users to band together and offer a cash reward for a torrent app. It got up to an astronomical $US90 before Torrent Droid claimed the prize. [Torrent Freak]