Cornell Chronicle: Interplanetary sundial heads for Mars as a calibration tool: Story regarding the color calibration tool intended for use on the cancelled Mars 2001 mission.
Mars Exploration Rover: NASA's latest news from Spirit and Opportunity. The primary goal of the robots is to search for and characterize a wide range of rocks and soils that hold clues to past water activity on Mars.
Mars Exploration Rover 3D: A 3D Rover model and landing site simulations.
Mars Exploration Rover Mission: Latest news, press releases, and photos from Spirit and Opportunity.
Mars Exploration Rovers: Clearinghouse of links for the Mars Exploration Rover Mission (Spirit and Opportunity).
Mars Rover Blog: Illustrated news journal of Spirit and Opportunity progress.
Missions to Mars: Cornell University's developments of the new generation rover for the 2003 Mars Exploration Rovers.
NPR : Mars Rover Marks Second Anniversary of Landing: On the two-year anniversary of mars rover Spirit's landing, both rovers (Spirit and Opportunity) are going strong. The robotic geologists have provided invaluable data about whether Mars could once harbor life. [7:33 streaming audio broadcast]
Space.com - Mars Rover Special Report: Collection of articles about Spirit and Opportunity published by space.com.