Epinions: Air Conditioners
Consumer reviews, price information, related appliances, buying tips and advice, ratings.
http://www.epinions.com/hmgd-Large_Appliances-All-Air_Conditioners

Warmair.com: Cooling Topics and Tools
Includes information on all aspects and variations of cooling, air conditioning, including consumer information on how these appliances work and what to look for.
http://www.warmair.com/html/cooling.htm

Carrier
Brand name product site. In addition to Carrier information, also has pages with consumer information such as what size air conditioners to buy for both home and industrial use.
http://www.global.carrier.com/

HowStuffWorks: Air Conditioners
Describes air conditioning from window units up to large industrial applications.
http://www.howstuffworks.com/ac.htm

SoYouWannaBuy.com: Air Conditioner
Step-by-step instructions on how to buy an air conditioner.
http://www.soyouwanna.com/site/syws/aircond/aircond.html

Refrigerant-22 Phaseout
EPA site with homeowner information for consideration when purchasing or repairing a residential system or heat pump.
http://www.epa.gov/ozone/title6/phaseout/22phaseout.html

HVAC Mechanic.com
Information and support on heating, ventilation and air conditioning systems or controls for home owners and professionals. Knowledge base, recalls, forum, glossary, and events.
http://www.hvacmechanic.com

Heating and Air Conditioning Buying Tips
From a sales site, consumer information on buying heating and air conditioning and on hiring a contractor for installation.
http://superior-air.com/buying_tips.htm

Consumersearch.com: Air Conditioners
The site identifies which products reviewers like and dislike, where they agree or disagree, and why.
http://www.consumersearch.com/www/house_and_home/air-conditioner-reviews/