The Big Pictures of Saturn, Mars and Ares I-X
Recently, the Big Picture at boston.com does quite a number of astronomy theme collections. Check them out below. I especially love those from Mars by HiRISE showing familiar landscapes (sand dunes, craters, ice caps) on an alien world.
Saturn at Equinox
Martian Landscapes
Launch of the Ares I-X
If you never visit the Big Picture before, I strongly recommend you do. There you can see a lot of hi-res images cover almost everything under the sky and up in the sky. They showcase the cultures of different countries, religions, festivals, history, art, health, nature, environment, natural disaster, war, sports and the beauty beyond our planet.
My Dark Sky 