Last.fm

During my beautiful 1 1/2 weeks off from work I finally got around to playing with some technologies / websites I'd been meaning to use for some time. last.fm was one and I cannot get over how incredibly kick-ass it is.

I'd tried to install the thick client a while back, but the beta version 0.9 wouldn't run on my Intel Mac Mini. No such problems with the current version.

last.fm is a little hard to describe. Basically, it is a streaming music service. However, it incorporates all sorts of Web 2.0ish things like tags. Furthermore, the client can detect what you're listening to in your desktop music players like iTunes or Windows Media Player. You can rate songs from the stream or your media player. It uses all this information to build a profile on your listening tastes. last.fm then uses collaborative filtering to figure out what other music you would probably like.

I've been a big fan of collaborative filtering since I first learned about it. When done right it can be astonishingly accurate. The recommendation system at Amazon.com is perhaps the best known example of this. I'm always amazed at how it can suggest rather obscure books, movies, or albums that I love.

Collaborative filtering works on the principle that you are likely to like things that other people who like the same things as you like. So if Alice and Bob both like The Roots, Mos Def, Common, and Talib Kweli, and Bob likes Little Brother, it is likely that Alice will also like Little Brother. Other types of recommendation systems try to use the qualities of the items themselves. For instance, you could do an analysis of the music itself and determine that two artists sound similar, so if you like one, you may like the other. I think that human taste is so varied and hard to quantify that this approach is doomed. This is the approach that competitor Pandora seems to be using. Interesting service, but I found last.fm better and with greater potential. Looking at comscore traffic ratings it seems that the internet agrees (and these are before last.fm came out with their flash based player):

On a side note, I thought I was really late to the party on this one, but apparently that was only amongst the nerdy programmer set. I mentioned last.fm to about 10 tech savvy but non programmer friends and no one had heard of it, but all loved it when they tried it.