I think JukeFly might fit the bill:
I've uploaded my collection to it but have only used it to stream a few times. Haven't really used it enough to be able to recommend it.
Listen to Your Music Anytime, Anywhere JukeFly allows you to stream your personal music library from your home PC running the free JukeFly software, to your Windows Phone 7 over WiFi or 3G* Features: - Stream your music from your PC running JukeFly software - View additional enriched content around your music, including artist bios, lyrics and videos - Easy setup means no fuss or technical knowledge needed for firewall or router stuff Windows Phone 7 Exclusive features - Built for Windows Phone 7 Metro UI look and feel - Social features for the music you’re listening to (Update your FaceBook wall, Tweet or send a Musicnote to your friends and show off the latest tunes you’re listening to.) - Offline listening – Carry on rocking to your tunes even if you don’t have a data connection. Specify playlists that you want with you all the time! If you’re new to JukeFly, all you have to do is sign up for a free account, install the JukeFly Personal Server on your PC and within minutes you can be streaming your entire music library. *Data connection plan required for streaming over 3G and data use and charges may occur.