Just Got a Chromecast: Any app Suggestions?

Basically the title says it all. I understand that google recently released the api to all android developers, expanding the possibilities of app functionality to a crazy high magnitude. But as of now, what are the most notable ones? And what are some tips and tricks you can tell me about Chromecast. Also, does any one know when that chromecast update for android mirroring releases? I thought they said sometime this summer, but forgot when.