Subsonic has been listed on the XSPF application page for quite some time. Now I took the time to give it a try and I'm amazed! You can use it to bring a structured view to you music collection or to let your friends stream and download music from your harddisc. Subsonic even downsamples on the fly if LAME is installed. Subsonic is running on top of Tomcat 5.5+, version 6 worked fine for me. With Java it's a little different: 6.x didn't make the service start, 5.x did. Give Subsonic a try, it's well worth it.