Scrobbler: A Last.fm Library for Ruby
John Nunemaker has put together a pretty tight library for accessing Last.fm data called Scrobbler. gem install scrobbler will get you most of the way there, and then you can quickly find recent tracks for any user, tracks for particular albums, and all sorts of great data. This could be a useful library for anyone putting together some sort of social networking or profile app in Rails who wants to show a user's recently listened tracks within their own system.