Knapster supports most of the napster protocol. It provides:
Search by name and group, including all of the search options of Napster.
Both upload and download types
Personal mp3 library panel
hotlists
User messaging
Chat channels
commands such as ping, whois, kick
In-built mp3 player and playlist
Inbuilt Napigator support
It can be used to connect to opennap and Napster servers.