Solution: All you need is SimplifyMedia and the popular iTunes media player - both are available for Mac and Windows. It is expected that SimplifyMedia will support WinAmp, Windows Media Player and other media player software pretty soon.
Update: The Simplify Media service is no longer available but you can use Amazon Cloud Drive or Dropbox to stream media.
It works like this - you add the music folders to SimplifyMedia watch-list on your home computer that contain the songs you would like to access or listen from other computers. When you are in office, you again login into SimplifyMedia and start iTunes where you'll find the same home music library under Shared Playlists. Hit play and the music or podcasts stream over the internet. Quite simple.
When you install Simplify Media software on additional computers, you are connected automatically when you log in with the same screen name. To share the music with other friends, you can invite them via email and they too can listen to our iTunes music playlists on their computers.
However, you cannot use this system to copy songs from the home computer to work or transfer them to the iPod. Other options for sharing your music collection on other computers via the web are Purple Nova and Dekoh Music.
Related: Turn Google Talk or Yahoo! Messenger into a Live Music Station