Transmission-QT is a lean, easy-to-use BitTorrent client with support for encryption, a web interface, peer exchange, magnet links, DHT, µTP, UPnP and NAT-PMP port forwarding, web-seed support, watch directories, tracker editing, global and per-torrent speed limits, and more. It is a free and open source BitTorrent client application that's minimalistic, advanced, light on system resources, efficient and reliable.
Here are some screenshots to illustrate the features and user interface of this application:
FrostWire
Tixati
BitComet
qBittorrent Portable
Freenet