The list of addresses that follow are current as of early Fall 2008 and should provide a useful start in a search for renewable energy information on these topics:

Biomass: General

Biomass: Biofuels

Biomass: Landfill Gas

Biomass: Municipal Solid Waste

Biomass: Waste-to-Energy

Biomass: Wood

Geothermal

Hydrogen: General

Hydrogen: Major State Programs

Hydrokinetic

Solar: General

Solar: Photovoltaic

Solar: Thermal

Wind

Renewables: General

American Council on Renewable Energy(ACORE)
http://www.acore.org/

California Energy Commission
http://www.energy.ca.gov/

Database of State and Federal Incentives for Renewable Energy
http://www.dsireusa.org/

Energy Information Administration
http://www.eia.doe.gov/

European Commission
A Global Overview of Renewable Energy Sources (AGORES)
http://www.agores.org/

Green Energy News
http://www.nrglink.com/

Green Power Market Development Group
http://www.thegreenpowergroup.org/

International Energy Agency
Renewable Energy
http://www.iea.org/

Interstate Renewable Energy Council
http://www.irecusa.org

National Association of Regulatory Utility Commissioners (NARUC)
http://www.naruc.org/

National Renewable Energy Laboratory
http://www.nrel.gov/

National Renewable Energy Laboratory
Energy Analysis
http://www.nrel.gov/analysis/

National Renewable Energy Laboratory
Publications
http://www.nrel.gov/publications/

National Renewable Energy Laboratory
Renewable Energy Analytic Studies Network
http://www.nrel.gov/reasn/default.asp

National Renewable Energy Laboratory
Renewables on Public Lands
http://www.nrel.gov/docs/fy03osti/33530.pdf

National Renewable Energy Laboratory
State Renewable Energy News
http://www.nrel.gov/analysis/sren/

Natural Resources Canada
http://www.nrcan-rncan.gc.ca/com/index-eng.php

Renewable Energy Atlas of the West
http://www.energyatlas.org/

Renewable Energy Businesses in the World
http://energy.sourceguides.com/businesses/index.shtml

Renewable Energy Nonprofit Organizations in the World
http://energy.sourceguides.com/businesses/byB/org/org.shtml

Renewable Energy Policy Project
http://www.repp.org/index.html

The Source for Renewable Energy
http://energy.sourceguides.com/index.shtml

U.S. Department of Energy (USDOE), Office of Energy Efficiency and Renewable Energy
http://www.eere.energy.gov/

USDOE Office of Energy Efficiency and Renewable Energy
EERE Financial Opportunities
http://www1.eere.energy.gov/financing/

USDOE Office of Energy Efficiency and Renewable Energy
Green Power Network
http://www.eere.energy.gov/greenpower/

University of California Energy Institute (UCEI)
http://www.ucei.berkeley.edu/

Biomass: General

Biomass Research and Development Initiative
http://www.brdisolutions.com/default.aspx

USDOE Office of Energy Efficiency and Renewable Energy
Biomass Program
http://www.eere.energy.gov/biomass/

Biomass: Biofuels

National Biodiesel Board
http://www.biodiesel.org/

Renewable Fuels Association
http://www.ethanolrfa.org/

U.S. Department of Agriculture
Farm Service Agency
Bioenergy Program
http://www.fsa.usda.gov/daco/bio_daco.htm

U.S. Department of Agriculture
National Agricultural Library
http://riley.nal.usda.gov/nal_display/index.php?info_center=8&tax_level=1&tax_subject=8

U.S. Department of Commerce
Bureau of Census
Current Industrial Reports
http://www.census.gov/cir/www/311/m311k.html

USDOE Office of Energy Efficiency and Renewable Energy
Alternative Fuels and Advanced Vehicles Data Center
http://www.eere.energy.gov/afdc/

Biomass: Landfill Gas

U.S. Environmental Protection Agency
Landfill Methane Outreach Program
http://www.epa.gov/lmop/

Biomass: Municipal Solid Waste

Solid Waste Association of North America (SWANA)
http://www.swana.org/

U.S. Environmental Protection Agency (EPA) - Wastes
http://www.epa.gov/osw

Biomass: Waste-to-Energy

Integrated Waste Services Association
http://www.wte.org/

Biomass: Wood

American Forest and Paper Association
http://www.afandpa.org/

Forest Industry Network
World-wide directory of forestry, logging, harvesting, saw milling equipment, etc. companies and related information.
http://www.forestindustry.com/

Regional Wood Energy Development Programme in Asia
http://www.rwedp.org/

Short-Rotation Woody Crops (SRWC) Operations Working Group: a private and public partnership between wood products companies, equipment manufacturers, utility companies, the U.S. Forest Service, the U.S. Department of Energy's Oak Ridge National Laboratory (ORNL), the National Council of the Paper Industry for Air and Stream Improvement (NCASI) and university researchers.
http://www.woodycrops.org/

U.S. Dept. of Agriculture Forest Products Laboratory
http://www.fpl.fs.fed.us/tmu/wood_for_energy/wood_for_energy.html

USDOE Office of Energy Efficiency and Renewable Energy
Forest Products Industry of the Future
http://www.eere.doe.gov/industry/forest/

Geothermal

California Energy Commission Geothermal Program
http://www.energy.ca.gov/geothermal/index.html

Geo-Heat Center, Oregon Institute of Technology, Geothermal Information and Technology Transfer
http://geoheat.oit.edu/

Geothermal Energy Association
http://www.geo-energy.org/

Geoexchange
Geothermal Heat Pump Consortium
http://www.geoexchange.org/

Geothermal Resources Council
http://www.geothermal.org/

Geothermal Resources Council
Geothermal Education Office
http://geothermal.marin.org/

Idaho National Laboratory Geothermal Energy website
http://geothermal.id.doe.gov/

Idaho National Laboratory
Geothermal Resource Maps
http://geothermal.id.doe.gov/maps/index.shtml

International Energy Agency
Geothermal Energy
http://www.iea-gia.org/

International Geothermal Association
http://iga.igg.cnr.it/index.php

Massachusetts Institute of Technology
The Future of Geothermal Energy
http://web.mit.edu/newsoffice/2007/geothermal.html

National Renewable Energy Laboratory
Geothermal Technologies Program
http://www.nrel.gov/geothermal/

USDOE Office of Energy Efficiency and Renewable Energy
Geopowering the West
http://www1.eere.energy.gov/geothermal/gpw/

USDOE Office of Energy Efficiency and Renewable Energy
Geothermal Resource Maps
http://www1.eere.energy.gov/geothermal/maps.html

USDOE Office of Energy Efficiency and Renewable Energy
Geothermal Technologies Program
http://www1.eere.energy.gov/geothermal/

Hydrogen: General

USDOE /Office of Energy Efficiency and Renewable Energy
http://www1.eere.energy.gov/hydrogenandfuelcells/

National Hydrogen Association (NHA)
http://www.hydrogenassociation.org/

Hydrogen Now!
http://www.hydrogennow.org/index.html

Clean Energy States Alliance
http://www.cleanenergystates.org/index.html

US Fuel Cell Council (USFCC)
http://www.usfcc.com/

American Hydrogen Association (AHA)
http://www.clean-air.org/

California Fuel Cell Partnership
http://www.fuelcellpartnership.org/

University of California – Davis (Hydrogen Pathways)
http://hydrogen.its.ucdavis.edu/

International Energy Agency
Building the Hydrogen Economy
http://www.iea.org/Textbase/work/workshopdetail.asp?WS_ID=311

International Partnership for the Hydrogen Economy
http://www.iphe.net/

Hydrogen: Federal Programs

USDOE
Hydrogen Program
http://www.hydrogen.energy.gov/

USDOE /Office of Energy Efficiency and Renewable Energy
Hydrogen, Fuel Cells and Infrastructure Technologies Program
http://www1.eere.energy.gov/hydrogenandfuelcells/

US Department of Defense (DOD)
Hydrogen Fuel Cell Test and Evaluation Center
http://www.fctec.com/fctec_about.asp

US Environmental Protection Agency (EPA)
Fuel Cells and Vehicles
http://www.epa.gov/fuelcell/ 

US Department of Transportation (DOT)
Hydrogen Portal
http://www.rita.dot.gov/agencies_and_offices/research/hydrogen_portal/

US National Renewable Energy Laboratory (NREL)
Hydrogen & Fuel Cells Research
http://www.nrel.gov/hydrogen/publications.html

Hydrogen: Major State Programs

California
http://www.hydrogenhighway.ca.gov/

Ohio
http://www.thirdfrontier.com/

Michigan
http://www.nextenergy.org/

New York
http://www.nyserda.org/programs/Research_Development/hydrogen.asp

South Carolina
http://www.schydrogen.org/

Texas
http://www.seco.cpa.state.tx.us/zzz_feulcell-initiative/fciachome.htm

Hydrokinetic

Electric Power Research Institute
EPRI Ocean Energy Program
http://oceanenergy.epri.com/oceanenergy.html#projects

European Commission Energy Programs
Atlas Project
http://ec.europa.eu/energy/atlas/html/wave.html

Federal Energy Regulatory Commission
Hydropower – Industry Activities
http://www.ferc.gov/industries/hydropower/indus-act.asp

Idaho National Laboratory
Hydrokinetic & Wave Technologies
http://hydropower.inel.gov/hydrokinetic_wave/index.shtml

International Energy Agency
Ocean Energy Systems
http://www.iea-oceans.org/

National Hydropower Association
http://www.hydro.org/

Ocean Power Technologies (OPT)
http://www.oceanpowertechnologies.com/

USDOE Office of Energy Efficiency and Renewable Energy
Exploring Ways to Use Ocean Energy
http://www.eere.energy.gov/consumer/renewable_energy/ocean/index.cfm/mytopic=50007

Solar: General

International Solar Energy Society
http://www.ises.org/

Solar Energy Industries Association
http://www.seia.org/

USDOE Office of Energy Efficiency and Renewable Energy
Solar Energy Technologies Program
http://www.eere.doe.gov/solar/

Solar: Photovoltaic

BP Solar
http://www.bp.com/modularhome.do?categoryId=4260

National Renewable Energy Laboratory
Photovoltaics Research
http://www.nrel.gov/pv/

PV Energy Systems, Inc.
http://www.pvenergy.com/

PV News
http://www.pvenergy.com/news.html

Sandia National Laboratories Photovoltaic Systems Research and Development
http://www.sandia.gov/pv/

Solar Electric Power Association
http://www.solarelectricpower.org/

Solar: Thermal

ASME (American Society of Mechanical Engineers) Solar Energy Di vision
http://divisions.asme.org/solar/

Sandia National Laboratories
National Solar Thermal Test Facility
http://www.sandia.gov/bus-ops/partnerships/tech-access/facilities/nsttf.html

Wind

American Wind Energy Association
http://www.awea.org/

British Wind Energy Association
http://www.bwea.com/

BTM Consult Aps
http://www.btm.dk/

Danish Wind Industry Association
http://www.windpower.org/en/core.htm

European Wind Energy Association
http://www.ewea.org/

German Wind Energy Association
http://www.wind-energie.de/en/

German Wind Energy Institute
http://www.dewi.de/dewi/index.php?id=1&L=0

National Renewable Energy Laboratory
Wind Research
http://www.nrel.gov/wind

Riso National Laboratory Denmark
Wind Energy Department
http://www.risoe.dk/vea

USDOE Office of Energy Efficiency and Renewable Energy
Wind & Hydropower Technologies Program
http://www1.eere.energy.gov/windandhydro/

USDOE Office of Energy Efficiency and Renewable Energy
Wind & Hydropower Technologies Program
Related Wind Links
http://www1.eere.energy.gov/windandhydro/wind_links.html

USDOE Office of Energy Efficiency and Renewable Energy
Wind Powering America
http://www.eere.energy.gov/windandhydro/windpoweringamerica/

USDOE Office of Energy Efficiency and Renewable Energy
Wind Powering America
Small Wind for Homeowners, Ranchers, and Small Businesses
http://www.eere.energy.gov/windandhydro/windpoweringamerica/small_wind.asp

USDOE Office of Energy Efficiency and Renewable Energy
Wind Powering America
Wind Resource Maps
http://www.eere.energy.gov/windandhydro/windpoweringamerica/wind_maps.asp 

Windpower Monthly News Magazine
http://windpower-monthly.com/