You should look at Orb Networks--"access your media from anywhere" i.e. anywhere you have web access. I believe I've seen one other program of this nature but can't remember where atm.

For anyone just interested in music, a very nice app is Twonky MusicServer--around 700kb and uses only 3Mb on your PC when running. As small a music Upnp as I've seen, and nice looking. You might have to search hard for it as Twonky Vision no longer makes this exceptional (free) sw available.