I just wanted to revisit this topic that I started.
I now have been using last.fm for a little under a year.
I now understand it better.
It's a musical discovery and social networking site!
1. If a listener likes a particular artist, they can check out the artist and his other works. There are usually links to purchase more.
2. If a listener likes a particular artist, they can find other artists that have similar sounds.
3. If a listener befriends someone else with similar tastes, they can discover artists on the friend's playlists.
4. Listeners are given a heads-up on live performances in their area by artists on their playlists!!! [Four Tet and The Residents are coming to Austin!]
5. Last.fm will compose an internet audio stream for the listener that consists of artists on one's playlist so that if I don't want to pick a CD or turn on my server, last.fm will do it for me. My music server (Squeezebox) even allows me to listen to this last.fm stream throughout the house by pressing one button.
6. I can listen to similar last.fm streams from any of my "friends" including other listeners and artists on last.fm.
7. I can contact artists via last.fm with questions and comments.
8. Last.fm allows me to visualize my listening habits in lots of cool ways:http://playground.last.fm/demo/musicuniverse/share?user=zzzoneDOTnet&seed=d0310http://playground.last.fm/demo/listeningtrends/share?user=zzzoneDOTnet&peers=none&palette=prairie&num_months=12
...and there's a bunch more cool stuff. All basically free or you can support the operation for 3 bucks a month.
I would encourage all the musical artists on hypnos.com to check it out and take over your wiki. The site encourages the legitimate sale of your music.