Stackexchange won't let me post comments, but I think it's worth mentioning that Ampache is something you should look into (on top of YoshiBotX's suggestions of a home server). It's similar to Subsonic. I have a time capsule 1TB from 2009 in bridge mode that stores all my art, music, and videos, and I pointed iTunes on my mac to it so that it looks for the iTunes library on that disk. I also set up fstab so that the timecapsule fileshare automounts into OS X (you can do this in Windows as well). The other thing I did was mounted my time capsule in Ubuntu on my web-accessible homeserver at home and have Ampache running on it and scanning the mounted filesystem. I then can stream music from web browser or to my Android phone.
The one thing I'll say is Ampache seems to struggle with 200 GB of music when it is indexing my library. It could also be possible that I have some weird filenames in there, too. I haven't messed with it much recently so they could have made it more stable.
I use TuneUp (an iTunes addon) for renaming my song files and cleaning up names/albums/artists. TuneUp is able to determine what to name and title a song based on just the sound signature of the file. I use GetLyrical for automatically fetching and applying lyrics to the .m4a and .mp3 files.
The only thing I've mentioned so far that costs money is TuneUp (and the time capsule and home server, but I got those for free). All the hosting I've set up is free as well.
I have also read that there are ways to share your iTunes library through the internet but I think my solution is more robust.
UPDATE- forgot to mention.. you will probably see a 3 second delay on accessing music if it's stored on a time capsule (or maybe a NAS that allows disks to sleep). The time capsule allows disks to spin down when they're not in use or when the music is cached to your PC so it has to spin up on first open. The advantage to this though is that I don't have to buy a 3 tb 2.5 hdd drive to fit in my laptop, so the tradeoff is worth it IMO. YMMV.
