BearShare
http://www.bearshare.com/
BearShare is an exciting new Windows file sharing program from Free Peers, Inc. that let's you, your friends, and everyone in the world share files!

Gnotella 
http://rocketdownload.com/details/musi/gnotella.ht
Gnotella is clone of Gnutella, a distributed real time search and file sharing program.

Gnucleus
http://gnucleus.sourceforge.net/
A Gnutella clone for windows with advanced features and security

LimeWire
http://www.limewire.com/
LimeWire is a multi-platform Gnutella client with nice features like auto-connect, browse host, multiple search, upload throttling, connection quality control, library management and sophisticated filtering.

Ohaha
http://www.ohaha.com/
A file sharing tool that uses all the networks out there (napster, gnutella, etc.) and works completely decentralized. Runs within IE5.

2 Find MP3
http://npssoftware.com/2findmp3/
2 Find MP3 is another example MetaCrawler software that searches both http and ftp and verifies the results.

Scour Exchange
http://www.scour.net/
This software is currently being redesigned and made 'legal'. Look for a new version soon

SongSpy
http://www.songspy.com/
A peer-to-peer software tool with it's own network and many napster-like features (for example a built-in mp3 player)

KaZaa Media Desktop
http://www.kazaa.com/
Another all-format peer-to-peer file sharing tool with all the usual features and it's own network

Audio Galaxy
http://www.audiogalaxy.com/
Both software (sattelite) to search usercollections at their own machines and a webbased search through user's personal online collections, which resides on the Audio Galaxy servers

Filetopia
http://www.filetopia.com/
Another tool with it's own sharing networks but offering real good security and levels of sharing. Has integrated email and im.

iMesh
http://www.imesh.com/
Yet another tool with it's own sharing networks. Many cool features like animated skins. Worth a try

Share Sniffer
http://www.sharesniffer.com/
Share Sniffer is a program that searches for Microsoft Windows machines on the internet that have opened their shares to all users without a password.

AudioGnome
http://www.audiognome.com/
Excellent piece of software that let's you connect to multiple napster-based servers at the same time

Napigator
http://www.napigator.com/
Generates a list of napster-based networks that are online and howmany gb's/users are present on the network.

WinMX
http://www.winmx.com
WinMX is a FREE file-sharing program like no other. It allows you to simultaneously connect to many established networks based on the OpenNap and Napster protocols.

Aimster
http://www.aimster.com/
Integrates with your AOL Instant Manager and let's you search Napster, Gnutella, AOL and MSN networks for files