Haven't seen this mentioned in many places but it deserves note. There is a nice streaming net jukebox on sourceforge called Netjuke. I installed it last week and am very impressed with its capabilities. Great for accessing a centralized MP3 collection on a LAN and even works over the internet from a remote location.
The setup involves and requires PHP and an SQL database - but I had no problems doing the setup with no knowledge of PHP or SQL. The developer is also very active and responsive.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20020115074026173