Last.fm makes personal radio stations easily shareable [DJ Alchemi]
I'm not a subscriber to Last.fm's paid/premium service, so I hadn't seen this (and can't yet implement it). But, David Jennings is showing of the beta of their new embeddable flash player. You, as the embedder (if that is a word), can set it up to default to any station you want (your personal station, recommendation station, neighbor station, tag-based station, etc.)
As the visitor to a site with this player, you can listen to the default station that the embedder set, or you can change the station yourself to virtually any "similar artist stations" by simply typing in an artist name.