I work for LimeWire. LimeWire is a nice combination of a really robust program and an easy-to-use interface. In particular, LimeWire handles multiple searches in an elegant way, and it just looks nice. Behind the scenes, LimeWire implements all of the most advanced features of Gnutella, such as UltraPeers, "HUGE" (with download meshes and hash support), swarm downloading, etc. LimeWire is also open source, and it benefits tremendously from the international community of LimeWire open source contributors. These users extensively test the code and make little additions/fixes. The open source mantra that "all bugs are shallow when given enough eyes" certainly holds true for LimeWire. It's a more robust program because of the open source community.

As always, there are several really powerful ideas coming down the pipe from LimeWire that will make the currently available program pale in comparison. Oh yeah, and LimeWire works on all operating systems.

http://www.limewire.com