The two things I don't see bittorrent utilized for nowadays are livestreaming, and file matching.
Sure, there's some demos of bittorrent live, but it's not hit the mainstream yet. 30-60 second stream delay should be plenty of time to sync video to everybody.
File matching would be neat too. Just scan your files against a DHT database and you'll never have to worry about losing them again. Just as long as there's seeds.
