Safari & AirTunes (AirPlay) extension?

Hi,
I have often wondered if I can connect what playing on my Safari (online radio which doesn't load in iTunes) to my AirPort Express. But a brief web search uncovered nothing out there for either a plugin or extension or setting to connect Safari to the AirTunes ability.
It seems like that would really be a cool thing to integrate.
Does anybody have advice or links to this? I can't be the only person who has thought of this...

thanks