RQL is a simple query language for last.fm that allows you to ask for more specific radio stations.
In URLs -- which the player understands -- the query text is encoded in Base64, so below is a tool to do that translation and let you play.
See some notes at http://helpful.knobs-dials.com/index.php/RQL
Editing these text fields will change the URL and link immediately.
You can click them to play, or drag to bookmark.