BitTorrent is the free official client for the eponymous protocol, peer-to-peer, and it's lightweight and full of features. It is also available for Android and Mac.
The official BitTorrent client
A very powerful and free piece of sharing software
The best file sharing site
Use your favorite torrent client anywhere
Free App for Media Lovers
The original Bittorrent client
Control your uTorrent downloads wherever you are
The latest beta version of the best P2P client for Mac
Free beta torrent software
A Free Internet program for Mac
Speak Freely. Person to Person.
A faster way to sync and transfer files