Plusbar adds couple of new things to Google+ like audio and video media player. Although the plans are pretty wide, at the moment plusbar offers Amazing Radio, DFH Radio, Grooveshark, BBC News and TWiT livestream. It integrates beautifully into Google plus as if it was a native part of the stream.
We are addicted to Google+ and spend hours on it, this is definitely a nice add-on to accompany the navigation. We love Chrome CSS tricks, check it out (chrome only).