Muujun

To be honest I’d stumbled across last.fm a few times when googling for various tracks around the place, but never really paid much attention to what it was or did (yea so I can be naive like that). But after a bit of investigation when I was bored, I worked out the whole point of it.
Without going into too much detail, it’s a bit of a social networking site, based primarily on the music people are into. You download a peice of software that sits stealthily on your PC (or Mac if you’re that way inclined) and it just pays attention to what you’re listening to in iTunes or Windows Media Player, and then reports it back to the site, thus anyone who views your profile can see what you’re into, and laugh at your pathetic/impeccable taste (as if anyone has impeccable taste in music).
The people behind the site can probably explain it better than I can though;

What is Last.fm?
Last.fm is a service that records what you listen to, and then presents you with an array of interesting things based upon your tastes — artists you might like, users with similar taste, personalised radio streams, charts, and much more.

What is Scrobbling?
Scrobbling a song means that when you listen to it, the name of the song is sent to Last.fm and added to your music profile.
Once you’ve signed up and downloaded Last.fm, you can scrobble songs you listen to on your computer or iPod automatically. Start scrobbling yourself, and see what artists you really listen to the most. Songs you listen to will also appear on your Last.fm profile page for others to see.
Millions of songs are scrobbled every day. This data helps Last.fm to organise and recommend music to people; we use it to create personalised radio stations, and a lot more besides.
You can see what Last.fm users listened to the most last week by clicking the Charts button at the top of the page. Add your musical taste into the mix and help us get some decent music into the top 10.

The best bit though I reckon, is that you can have it output your recently listened to records to a .gif image, so you can whack it on your myspace/website/blog whatever, and everyone can have a good old butchers at what you’re listening to. (it’s always updated automatically, through internet magic)
eg; here’s the last ten tracks I’ve listened to on the old iTunes player thing…

 

So yea, thats pretty much it. Sign up, listen to some songs, everyone elses see’s what you’re listening too, and maybe reccomends stuff that’s similar, and the best bit is that the site will even point you in the direction of people who are into similar stuff to you, so you could end up talking to John Peel’s ghost, or a bloke called Dave who’s into The Village People.