Shareaza

Shareaza has unique features, including ghost ratings, a completely user-configurable queue area, and multinetwork support. The program started as a Gnutella client but recently branched out and developed Gnutella2, a completely open and documented network. Shareaza's interface is easy to use, yet powerful and fully skinnable. Shareaza's download core was built to provide optimum performance from any number of sources. Shareaza can manage your download queue automatically, or you can take charge and modify the status of files or even individual physical transfers and sources.

BitComet

BitComet is a fast and easy-to-use BitTorrent/HTTP/FTP download client. It is P2P file-sharing freeware and one of the most popular P2P protocols designed for high-speed distribution. BitComet supports simultaneous downloads, DHT networks (trackerless), a download queue, selected downloads in the Torrent package, fast-resume, disk caching, speed limits, auto port mapping, proxies, and IP filtering.

eMule

eMule is one of the biggest and most reliable peer-to-peer file sharing clients around the world. Thanks to it's open source policy many developers are able to contribute to the project, making the network more efficient with each release. eMule is a filesharing client which is based on the eDonkey2000 network, but offers more features than the standard eDonkey client.

Azureus

Azureus is a easy-to-use Java BitTorrent client, with support for 27 languages. Azureus connects to the BitTorrent network. BitTorrent is a peer-to-peer protocol designed to transfer files. Users connect directly to send and receive portions of a file, while a central tracker coordinates the action of all peers and manages connections without knowledge of the contents of the files being distributed. With BitTorrent, users upload at the same time they download, so network bandwidth is managed as efficiently as possible. BitTorrent is designed to work better than other file-transfer protocols as the number of people interested in a certain file increases.

uTorrent

uTorrent is a powerful and efficient BitTorrent client for Windows. Most of the features present in other BitTorrent clients are present in uTorrent, including bandwidth prioritization, scheduling, RSS auto-downloading, and Mainline DHT. Additionally, uTorrent supports the protocol encryption joint specification and peer exchange. Unlike many torrent clients, it does not hog valuable system resources--typically using less than 6MB of memory, allowing you to use the computer as if it weren't there at all.