Life Extraterrestrial: Life on Other Planets in the Solar System
   Curriculum framework for comparing Earth to other planets with regard to life.
   http://www.resa.net/nasa/

Search for ET!
   Interactive Flash tutorial exploring the possibility of and search for life on other worlds.
   http://jvsc.jst.go.jp/universe/et_e/index_e.htm

The Planetary Society
   A nonprofit organization devoted to the exploration of the solar system and the search for extraterrestrial life.
   http://www.planetary.org/

The Rise and Fall of Star Faring Civilizations in Our Own Galaxy
   Speculation, based on the Drake Equation, regarding the existence and composition of alien civilizations.
   http://www.jrmooneyham.com/ctcta.html