This is a bit of old news, but still worth mentioning in case you haven’t heard. Pandora is still the most popular service for online music streaming. However, facing increasing competition from the likes of Spotify, Rdio, MOG, turntable.fm, etc, Pandora has responded by removing its 40 hour listening cap and launching a fresh new web interface.
I only use Pandora on my daily commute so I’ve never run into the 40 hour listening cap myself, but I’m sure this is good news for anyone who listens to Pandora at work everyday. Get listening!