BTAccel.com is probably one of the most innovative and useful sites to ever touch the bittorrent world. It’s general purpose is to do all the bittorrent on their server and then send the user an email when the torrent is done. This action in itself saves the user plenty of time when 1)bandwidth is limited 2)away from home PC 3)one does not want home PC on all the time.
Although the rates at which Btaccel grabs files is impressive, there are some caveats. In an attempt to spare processing/bandwidth power, btaccel will remove torrents that it cannot connect to after 30 minutes of inaccessability. Other times, btaccel might not even download or start the torrent (or report accurate seeder/leecher statistics) when the user has handpicked a very healthy torrent (cause unknown).
While the site is within the alpha stages, one can gain an invite by asking for one on the website itself or following them on twitter.
Main site: http://btaccel.com