Most music-streaming services offer some kind of Wikipedia-style write-up on the artist that's currently playing. Shuffler.fm does one better, switching between music blogs in your chosen genre and streaming tracks from recent posts. In other words, it's a more music-nerd-y Pandora.
In practice, shuffler.fm sits as a music control bar at the top of each blog page, providing controls to skip back or forward, pause the playback, switch genres, or email, tweet or "Like" a track on Facebook. Like what you're hearing? The blog post likely centred around the artist, song or event from which it came is right there in your browser tab. You get free music, a good vibe from patronising smaller-scale music blogs, and you don't even need to create a free account to listen.
Shuffler.fm is a free service and seems to require only a browser with Flash capabilities.