I tried last.fm years ago and had to give up. I was on my phone and read about a Swedish prog rock band, thought about how I could get to hear them and signed up for last.fm there and then. The service used that seed to give me a really fun scandanavian hippy rock experience exploring related bands from Finland, Norway and Denmark. It was great for a while, but then I was trapped. No matter what I did to push the service towards a more balanced assessment of my musical tastes, it kept casting me back into nordic psychdedelia hell.