Mars Exploration Rover Opportunity will be celebrating its third anniversary on mars next week. Opportunity  landed on 25 January 2004 on Meridiani Planum. To commemorate the anniversary NASA is hosting a photo contest to choose the best Spirit and Opportunity pictures (out of a pre-selected 16 images), then will show the winner on the MER home page on 24 January.

My vote is for Sprit's picture of the Sun setting over the Gusev Crater -- lonely, melancholic, elegant.