µTorrent 3.4.6.41911 Beta + Portable | 2.2/3.6 Mb
µTorrent is one of the most popular BitTorrent clients, with plenty of features such as bandwidth prioritization, RSS auto-downloading, scheduling and Mainline DHT (which is compatible with BitComet, another well-known BitTorrent client), Protocol Encryption joint specification (used also by Azureus, BitComet) and peer exchange.