BioMARS - A University of California Berkeley-led NASA Astrobiology Institute working to identify the types of sites on Mars that experienced long-term fluid flow as these may be, or have been, conducive to life.
MarsNews.com: Life on Mars? - Ongoing collection of news articles addressing the question as to whether or not life has, or does, exist on Mars.
NASA's Mars Exploration Program - NASA's home for all Mars missions past, present, and future. Aims to determine if life ever arose on Mars, characterize its climate and geology, and prepare for human exploration.