http://www.geoexchange.org
The Geothermal Heat Pump Consortium is a nonprofit organization working to raise awareness and increase the use of geoexchange technology throughout the United States.

http://www.igspha.okstate.edu
The International Ground Source Heat Pump Association (IGSHPA) is a non-profit, member driven organization established in 1987 to advance geothermal heat pump (GHP) technology on local,state, national and international levels.

http://www.unitedpower.com
United Power provides electrical service for areas of the Denver metro. United Power understands the benefits and cost savings of geothermal heat pumps. They provide rebates of $2500 per heat pump with additional rebates for installation and hot water heaters.

http://www.eere.energy.gov
This site provides general information on different types of renewable resources and energy efficient products.