I have just released MP3Mystic, a personal MP3 server that allows streaming as well as downloading MP3s accross the net. It is simple to set up (3 options to get you going), but very customizeable.
And as always if you haven't looked at my software for the car check out mp3it at www.mp3it.net.
mp3it - MP3 Software for Small LCD Screens for use in the car.
<A HREF="http://www.mp3mystic.com" TARGET=_blank>
MP3Mystic</A> - a personal MP3 Server software for windows.