Want to listen to your large library of music without putting the collection on your mobile device? I was looking at some apps for my iPhone 4 in the iTunes App Store using the Genius tab, which suggests apps based on apps you already have and came across this cool free one.

It’s called Audiogalaxy and lets you stream your music library from your computer to your iOS or Android device. It works over WiFi or 3G service.

When you sign up, you download a small helper file to the computer where your music is, in my case my iTunes music library with almost 7000 songs on my iMac at home. That’s where my master music collection resides. It works on both PC and Mac.

Once you have your free account, you can login to Audiogalaxy in your browser (works on most browsers) and it will start scanning your music in. Go have a cup of coffee and surf the web as this will take a while.

After the music is scanned in, the fun begins. You can play your music from the browser on any computer that you have logged into Audiogalaxy with. You can now also stream your music from your mobile device using the free Audiogalaxy app you download. Your computer with the music must be on and not in sleep mode for it to work.

I tried this at my job at UT Dallas, where they have a robust firewall and it worked great all over campus switching from 3G to WiFi as I went on my daily walk across campus with my headphones on. I never lost the streaming signal.

When you open the iPhone app, you get lots of choices of how to view your library. As you scroll through your collection it streams the little album icons if there was one (fast). Here you see it bringing in the last two in this page of albums.

The only thing I see missing is a view by song name, which would be helpful like I get in my iPod app on the phone. You can also save playlists of songs you have listened to in the app.

The Audiogalaxy web site gives all the details of what the service can do better than I can here, so go take a look. See Audiogalaxy in the Apple iTunes App Store and Audiogalaxy in the Android Market.

Yes, Audiogalaxy was a file sharing service back in the early 2000′s, which was shut down. It has been resurrected by three UT Austin former students, two of whom, worked on the original file sharing site.

Is there a reason not to download and try out this free app? I can’t think of one.