For those of you using XBMC, you might want to check out XBMCtorrent then [1]. It does exactly what the name says, while not depending on a service to do the download: select a torrent, watch it.

Disclosure: I'm the author

[1] http://forum.xbmc.org/showthread.php?tid=174736

[2] http://www.youtube.com/watch?v=NQiC62ig3N0

EDIT: URL was wrong