I recently purged a bunch of stuff I don't listen to anymore, at all -- and my main listening program is now Rdio, so I haven't built on my MP3 collection as much.
16532 songs, 89.95 GB.
That's roughly mine, but there is so much that I don't listen to anymore. I just keep it on there because I know the minute I delete it I will want to listen to it.
Haven't checkout out Rdio, i'll give it a whirl.