At the moment I'm runnig NZBGet mobile to download media from usenet to my external HDD which is mounted using Stickmount. By installing python for android I managed to get VideoSort to work, which is a script which automatically recognizes the TV-Show/Movie for you and names it accordingly, moves it and cleans up any left-over thrash. Works very well so far.
Combined with some usenet indexing site which build rss feeds (or remote push to NZBGet) for any new episodes/movie releases you can automatically download any new stuff which you might want. Some even import any stuff from your Trakt/IMDB watchlist. As XBMC is running on the same machine it is also easy to let XBMC update the library when any new media is added.
Wonder if anyone else has set up anything like this? I looked into installing transmission through optware on the FireTV but couldn’t install optware as it wouldn’t let me remount. Can install uTorrent and control that from your phone but as far as I saw I couldn’t get it to run a cleanup script after any download is done. Really want it to be all automated so for now I’m only using usenet, which I prefer over torrents anyway.