Okay back out of here now, you aren't helping by keeping the crap stirred up. You said your piece now move along!
I've not used LastFM myself, but I did notice it was available via an application on my iPod Touch. Just never really got around to messing with it yet.
This forum is for all forms of digital services, so I appreciate the OP bringing this up and those that are interest by all means check it out and/or make your comments. If that service isn't for you, then say your piece and move on.
Thanks,
The thing I like about Last.FM is the app will "scrobble" (send to your profile on last.fm as what you last played in your recently played list), after X amount of songs you scrobble it will start grouping you w/ other users w/ similar musical interests and rate your music compatibility.(neighbors) Start making charts based off the artists you played.
You can make your own playlists/radio stations also. People can listen to "your" radio station via the Last.FM app(or in browser but the app is preferred so it scrobbles everything). Or you can listen to others playlists or music library. Whether you are listening to songs via iphone, ipod, winamp, someones playlist, someones library, a groups radio station, it's constantly scrobbling what you listen to and expands your library of tracks.
Think of it as a social networking site based around music w/ a pandora(esk) interface and then some. It's free and works extremely well.
My profile for an example
http://www.last.fm/user/styckx