I had a pretty large music collection – about 50GB. I honestly don’t even know how I got some of it, and there are undoubtedly songs I have and have never heard.
Over the course of several years, I have tried to rate all of the songs in my collection. Sometimes this was so I knew what to sync to my mp3 player with less storage than the full collection. Sometimes it was because I wanted to actually try to listen to all of it, and rating it as I went was the best way. Sometimes it was because I actually wanted to weed out the collection; deleting the stuff I had but didn’t actually like.