Space.com has a nice article on the two rovers that are still going strong on Mars.

Those peppy Mars rovers, Spirit and Opportunity, continue to make tracks as they wheel about two diverse locales on Mars – far outstripping their original warranties of 90 days of lifetime and a target of roughly 2,000 feet (600 meters) of driving range when they landed on the planet in January 2004.

Both of the mechanized emissaries from Earth remain hard at work, said Steven Squyres, principal investigator for the NASA Mars Exploration Rover Project and astronomer at Cornell University in Ithaca, New York.