Whether you have a torrent client on your NAS device or on your desktop, Transdroid is a nice way to manage your torrents from your phone. All popular clients are supported, including µTorrent, Transmission, rTorrent, Vuze, Deluge and BitTorrent 6. You can view and manage the running torrents and individual files. Adding is easy via the integrated search, RSS feeds or the barcode scanner. Monitor progress using the home screen widget or background alarm service.
Last time I checked it had been pulled from the Android market, however if you download directly from their site you can install without problems. I’ve been using it for several months with Transmission installed on my NAS–a WD MyBook World Edition–and it is one helluva tool.