AAO-HNS
Everything you need to know about ears, earache, ear infections and the effects of altitude.
http://www.entnet.org/healthinfo/ears/

Boeing.com
An overview of cabin air systems on airplanes.
http://www.boeing.com/commercial/cabinair/

Bose
Find out more about the firm's QuietComfort acoustic noise cancelling headphones at this official website.
http://www.bose.com/

Cirrus
Cirrus market an ear pressure regulating ear plug.
http://www.earplanes.com/
http://www.cirrushealthcare.com/

Etymotic Research
Etymotic's range of noise-cancelling Isolator earphones are perfect for listening to music on board airplanes or trains.
http://www.etymotic.com/

Flyana.com
Advice on how to unblock ears in airplanes.
http://www.flyana.com/ear.html

Health Considerations
Advice on how to employ the Valsalva Maneuver to clear your ears by make them pop.
http://www.websciences.org/dvhpub/health.htm

Health Nexus
Links to sites with information on ear ache and treatment for it.
http://www.health-nexus.com/ear_ache.htm

PhysLink.com
An explanation of why your ears pop when you are riding in an airplane.
http://www.physlink.com/Education/AskExperts/ae37.cfm

USA Today.com
Information on Barotitis Media/Aerotitis, an inflammation of the ear caused by changes in atmospheric pressure.
http://www.healthscout.com/ency/68/438/main.html

Video Jug
A short video explaining how to relieve an earache caused by flying.
http://www.videojug.com/film/how-to-relieve-an-earache-caused-by-flying