General information about home engery audits:
http://www.energystar.gov/index.cfm?c=home_improvement.hm_improvement_audits

Instructions on do-it-yourself home energy audit:
http://www.energysavers.gov/your_home/energy_audits/index.cfm/mytopic=11170

Professional home energy audit:
http://www.energysavers.gov/your_home/energy_audits/index.cfm/mytopic=11180

Web-based energy audit:
http://hes.lbl.gov/

Questar Gas home energy audit program:
http://www.thermwise.com/home/Audit.html

General energy saving information from Provo City Power:
http://www.provo.org/util.util_main.html

Department of Energy home energy checkup and audit information:
http://ase.org/section/_audience/consumers/homecheckup

Video on how to change a furnace filter:
http://www.ehow.com/video_4419527_change-furnace-filter.html

Thermwise furnace tips from Questar Gas:
http://www.thermwise.com/tips.html

Video on how to replace a furnace filter:
http://www.ehow.com/video_4984882_clean-replace-furnace-filter.html