Nap is a text-based Napster client for Linux. It was historically one of the first available Napster clients, and is very stable. It is a fully-featured client, and compiles on Linux, *BSD, Windows/Cygwin32, and Mac OSX.
capster is the first multi-platform GUI napster client. it has more features than even the well-featured windows client. it can be run on windows, unix, mac... any OS for which there is a Tcl/Tk runtime.