Best Mars Images From Orbiter’s First 5 Years

"Since settling into orbit around the Red Planet on March 10, 2006, MRO has transmitted more data to Earth -- 131 trillion bits and more than 70,000 images so far -- than all other interplanetary missions combined.

After the orbiter finished all its initial science objectives in the first two years, NASA extended its lifetime twice. The extra time let MRO watch Mars change over two-and-a-half Martian years, giving a new picture of a shifting, dynamic planet."

http://www.wired.com/wiredscience/2011/03/happy-birthday-mro/