Windows only: Popular BitTorrent client uTorrent just released its 2.0 release candidate yesterday, complete with UDP tracker support and a new transfer cap feature to help you monitor your bandwidth usage — and video streaming is in the works for 2.1.
The UDP tracker support has been added to lower the resource load on the tracker end, allowing torrent sites to support more users without slowing (see our post on the 2.0 beta release for more details on UDP). uTP support has also been vastly improved in this version, allowing the client to automatically regulate bandwidth usage so you can download your torrents without slowing down the network for others — no messing around with preferences required.
Possibly the most useful feature, though, in the new 2.0 release candidate is a transfer cap, so you can keep track of how much bandwidth uTorrent is taking up over a defined period of time, and even tell uTorrent to stop torrenting once you reach certain limits. This should come in extremely handy for users whose ISPs are capping their bandwidth — now you don't have to worry about exceeding your cap.
Also worth mentioning is the uTorrent 2.1 alpha release, which shows the first signs of a video streaming feature, which would allow you to begin watching videos as you're downloading them — very useful for those who want to watch something now, but don't want to wait for the whole download to complete. You can even configure it to stream through your favourite media player, like VLC or Windows Media Player.
uTorrent 2.0 RC1 is a free download, Windows only.