I love services that passively record things I do. So I was excited to find Audioscrobbler from last.fm. It silently watches my Winamp and Squeezebox traffic and tells a server what I'm listening to. Simple, well executed.
What last.fm is missing is doing anything useful with that data. The site has some complex dashboard social network thing that is impenetrable to me. And it has a music recommendation function which is pretty good, but too junked up by crappy quality free music to be enjoyable.
So hooray for third party graphs! lastgraph is a simple web site that plots your music listening history from last.fm. The tool is a bit awkward, but the resulting graphs are beautiful and readable.
I hope last.fm has already made the appropriate overture to provide these graphs themselves. Simplify the creation tool a bit, publish a PNG, and fix poor Édith's name and you've got a fine product feature.