2005 - Mars Reconnaissance Orbiter
http://marsprogram.jpl.nasa.gov/missions/future/2005.html
NASA's Mars Reconnaissance Orbiter, scheduled for launch in 2005, will be equipped with cameras to zoom in for extreme close-up photography of the martian surface, carry a sounder to find subsurface water and look for safe and scientifically worthy landing sites for future exploration.

Phoenix
http://marsprogram.jpl.nasa.gov/missions/future/phoenix.html
In May 2008, the progeny of two promising U.S. missions to Mars will deploy a lander to the water-ice-rich northern polar region, dig with a robotic arm into arctic terrain for clues on the history of water, and search for environments suitable for microbes.

Mars Science Laboratory
http://marsprogram.jpl.nasa.gov/missions/future/msl.html
NASA proposes to develop and to launch a roving long-range, long-duration science laboratory that will be a major leap in surface measurements and pave the way for a future sample return mission. NASA is studying options to launch this mobile science laboratory mission as early as 2009. This capability will also demonstrate the technology for "smart landers" with accurate landing and hazard avoidance in order to reach what may be very promising but difficult-to-reach scientific sites.