MP101 by Netgear

http://en.wikipedia.org/wiki/MP101

SounBridge Roku

Linksys NSLU2

http://en.wikipedia.org/wiki/SlimServer

http://www.roku.com/netflixplayer/support/

http://www.roku.com/support_sb.php

http://www.allegrosoft.com/amsfaq.html

ElGato software comes as a demo ; yet, the music function can still be used after the trial expires.
http://www.elgato.com/elgato/int/mainmenu/products/software/EyeConnect.en.html

More solutions are listed in this post
http://www.avforums.com/forums/archive/index.php/t-241486.html


http://tech.groups.yahoo.com/group/NetgearMP101Group/
http://tech.groups.yahoo.com/group/NetgearMP101Group/files/TwonkyVision%20Server%20Software/

http://www.netgear-forum.com/forum/index.php?s=1bf4d0f830e9829bdc99e8448a709716&showforum=214


Cidero Software
http://www.cidero.com/downloads.html

Tiniest PC ever seen

http://www.pcpro.co.uk/blogs/2008/08/27/a-real-space-oddity-arrives-at-pc-pro/