All open Source Napster Server: Open source file sharing clients
Java clone: Java clone for mp3 file sharing
MP3 Easy: Search software competitive with Napster, and untraceable. MP3 music from any song/artist can be downloaded at the touch of a button.
NoNap.8m.com: Offers alternative file-sharing programs to Napster, with ratings and network information.
ZDNet's Ultimate CuteMX Guide: CuteMX is designed to be a simple way to swap files, easier than Napster and as powerful as Gnutella. Article explains the program and its features.