The NASA Visualization Explorer on Facebook has some cool images of our solar system, and via the Hubble space telescope: our vast universe.
JPL has its own YouTube channel here, including the 7 minutes of terror video about the MSL (Curiosity) landing.
www.spaceflightinsider.com (in affiliation with the National Space Society) has space news and a cool mission monitor to see live streaming of rocket launches. The Antares rocket is due for liftoff this Friday (with Cygnus aboard) at about 11:40am PDT, so go take a look at the mission monitor and watch that rocket take off for the International Space Station.
7/11/2014 – The Antares liftoff has been delayed 24 hours due to weather