The SETI Institute provides explanations of current work in this field and descriptions of current and future projects.
The SETI League is a non-profit organization you might be interested in. Their purpose is to encourage and coordinate SETI research.
Contact, the website for the movie, has links to SETI sites. (Be patient while the intro pages load.)
Project Beta is the project name of the SETI work done at Harvard.
Project Serendip is the project name of the SETI work done at UC Berkeley.
These space colonization links are so comprehensive it was silly to try to recreate them.
The Face from the Cydonia Region is a topic that many people have heard about.
Life on Mars? homepage is brought to you by the Federation of American Scientists
The Extrasolar Planets Encyclopedia is available from on of the two groups most active in the field.
NASA's Jet Propulsion Laboratory has many links related to NASA's plans for further investigation efforts.
Falling into a Black Hole simulation, produced by Andrew Hamilton.
Interactive Simulation of Galaxy Formation is run on George Mason University supercomputers.