MPD is pretty popular too http://www.musicpd.org/
It has a client/server model and you can create your own music streaming service by controlling it remotely and streaming back over http.
ncmpc/ncmpcpp is a client for mpd that resembles cmus quite a lot.
I use cmus too. For those who don't know it is a command line music player with a VIM-like command line interface ("/" to search, ":set x=x" to set various options).