The Spaceward Foundation: 
www.spaceward.org 

The International Space Elevator Consortium (ISEC): 
http://www.isec.info/welcome 

NASA Centennial Challenge Program: 
http://www.nasa.gov/offices/ipp/innovation_incubator/centennial_challenges/index.html 

Technical University Munich - Scientific Workgroup for Rocketry and Space Flight:
http://www.warr.de/projects.php?typ=space_elevator 

Technical University UPC Barcelona - Team Recens: 
http://www.domitech.es/recensteam/index.html

JSEA: Japan Space Elevator Association
http://www.jsea.jp

Ted Semon's Space Elevator Blog
http://www.spaceelevatorblog.com

Lunar Regolith Excavation Challenge
http://regolith.csewi.org

Mars Society
www.marssociety.org