Oddly enough, this is the app that made me realize that Chrome puts a recording symbol next to the name of the page when a page is using your microphone now (kind of like when they put the speaker icon on tabs that are playing sound). I think that's pretty cool!

http://i.imgur.com/GV5TktA.png

Edit: I should also mention that this is really well done, and I've been looking for something simple like this for a while. Thanks for sharing!