http://www.nrel.gov
The site for the National Renewable Energy Laboratory in Golden, CO. NREL is where huge amounts of our tax dollars get spent looking at wacky new solar technologies or the latest and greatest fuel cell design. The site is very deep, with lots of hidden gems, but not well organized.

http://www.solarbuzz.com
SolarBuzz.com is a solar information website run by a small solar consulting group, and it’s one of the few places around that actuall tracks the prices of solar cells across the industry.

http://www.cleantech.com
The Cleantech Venture Network is the premier membership organization for venture capitalists and investors interested in Clean Technology. The management are friends of mine, and have done more in the last few years for getting new technologies funded and pulling together investor interest in the sector than just about anyone.

http://www.fuelcelltoday.com
This is a site from the UK with a global focus. Of all the fuel cell sites out there it has the best news, a massive directory of people, and great links resources. It’s the only fuel cell site I read.