I used ourTunes in the dorms, people just sharing their entire iTunes with the network. I've always been more of a solo digger, but I never liked Spotify. I have specific dance/electronic tastes so I browse and purchase music on sites like bandcamp or beatport, though actually these days it's strictly junodownload.

I do wonder though how much of what you describe, or some form of it, is still happening in dorm rooms. As we get older we just do less of that kind of stuff. I still connect with a large circle of friends through music, and discuss different artists and such, mostly at events.