General:

• Energy Production / Consumption - World Resources Institute
• Entek International
• Polyplus Battery Company

Fuel Cells:

• Fuel cells - DOE site
• Fuel cells - National Fuel Cell Research Center Site
• Fuel cells - "How stuff works" site
• Fuel cells - American history site
• Ballard Power Systems
• Milennium Cell
• NH₄BH₄

Capacitors and Supercapacitors/Ultracapacitors:

• Capacitors - History and general info site
• Capacitors - some background slides
• Capacitors - basic physics
• Maxwell - manufacturer of ultracapacitors
• Capxx - another manufacturer

News:

• HP recall 2005
• Thirst for power 2005

Some online data sources:

• US DOE Office of Science and Technical Information (OSTI)
• OSTI - Energy files
• US DOE EERE Hydrogen Fuel Cell

Please let me know if you find interesting links to add!