The websites of  fuel cell manufacturers:
Ballard fuel cells, Plugpower, IFC, H-Power, Nuvera 
A very nice Fuel Cell flash animation - Learning module (US Department of Energy)
An educative site on biofuel cells by dr. Eugenii Katz
The online fuel cell information center: Fuel Cells 2000 
Website of  the World fuel cell council
Information on techniques and implementation of hydrogen and fuel cells
Website of the National Fuel Cell Research Center
Website of the Ceramic Fuel Cell Technologies
Information on solid oxide fuel cell technology
Website of the Dutch fuel cell company Nedstack
Information on fuel cells by various companies:
Dais-Analytic Power Corp
Nefit
Global Thermoelectric
Sulzere Hexis
InDEC BV
Siemens Westinghouse