last.fm is great for this. Type in an artist/genre you like and for the next few hours while you work, you will discover plenty of new ones as their radio service works by molding a 'radio service' to your taste.
http://unop.co.uk/dev/spotify-playlist-generator/
I'd be interested to know if it works everywhere. It still works in the UK.
EDIT: Source code: https://github.com/jpsingleton/Spotify-Playlist-Generator