Local to Boston are
www.wgbh.org and
www.whrb.org , which do stream 24x7. Of course, I don't listen at work and there's no need at home, where I have a radio. Others might like it, though. WHRB is famous for its orgies, which are run around exam time.
If I were really organized, I would take a methodical spin through the BBC and various European stations. Every so often in the summer, a classical music board I once frequented would post an announcement that the latest performance of X or Y was about to start live at Bayreuth. Seems as good a use for the technology as any other.