Ok This is really cool — a uPnP media server that might not suck and is free!
MediaTomb is an open source (GPL) UPnP MediaServer with a nice web user interface, it allows you to stream your digital media through your home network and listen to/watch it on a variety of UPnP compatible devices.
Currently Supported Features
browse and playback your media via UPnP
metadata extraction from mp3, ogg, flac, jpeg, etc. files.
Exif thumbnail support
user defined server layout based on extracted metadata (scriptable virtual containers)
automatic directory rescans
highly flexible media format transcoding via plugins / scripts
sophisticated web UI with a tree view of the database and the file system, allowing to add/remove/edit/browse your media
support for external URLs (create links to internet content and serve them via UPnP to your renderer)
support for ContentDirectoryService container updates
Active Items (experimental feature), allows execution of server side scripts upon HTTP GET requests to certain items
highly flexible configuration, allowing you to control the behavior of various features of the server
support for Linux, FreeBSD, Mac OS X
runs on x86, Alpha, ARM, MIPS, Sparc