I discovered a really great French radio station recently, France Inter Paris (FIP). It's got a quite unique format, playing blocks of themed music grouped roughly into styles. You tend to hear a half hour or so of music within a style, and the range of styles is incredibly eclectic.
Between 07:00 and 23:00 French time, a short news bulletin is run at ten minutes to the hour, and a dulcet-toned French woman will give a short background to the music. Otherwise it's pretty much advert and long talk free.
My only criticism is that outside the live announcer hours, you can't find out what music they're playing on the web site. Even when the music is listed, the stream is quite a bit out of sync with what's listed on the site.
Anyway, give FIP a go. It streams in high quality mp3 online.
Also an interesting read is the Wikipedia article, including details of the long-running pirate transmitter in Brighton, England.