The FastTrack network is a popular P2P net used by the spyware-ridden KaZza client and various unauthorised derivatives like KaZza Lite. It is popular because it is fast and easy to use, but offers no anonymity.
Organisations such as the RIAA and MPAA continue to demonstrate this fact by their ongoing campaign of launching large numbers of financially crippling lawsuits of dubious legality against sharers of copyrighted material.