AirSafe.com
Airline rules for unaccompanied children.
http://www.airsafe.com/kidsafe/kidrules.htm

Biztraveler.org
Provides a summary of the policies of major American airlines on children travelling alone.
http://www.biztraveler.org/rights/index.cfm

British Airways
Information on travelling with children, or sending them solo, on BA.
http://www.britishairways.com/skyflyers
http://www.ba.com/skyflyers

Child Safe
Aims to provide practical advice and promote the safety, welfare, and pastoral care of young people involved in travel, sport, community groups and specific school programmes.
http://www.child-safe.org.uk/

directmoving.com
Tips on flying with kids provided by an excellent expatriate travel site.
http://www.family-children.directmoving.com/

Geocities.com
Advice on how to arrange a trip for an unaccompanied minor, and an outline of the rules of major US airlines on young passengers .
http://www.geocities.com/travelwithyour/alone.html

Gulf Air
The airline provides Sky Nannies on board its wide bodied jets plying long haul routes, who look after your little ones while you take a break.
http://www.gulfairco.com/air/skynanny.asp

Hotelfun4kids
Find out what different airlines offer kids, both in-flight and when they are travelling as unaccompanied minors.
http://www.hotelfun4kids.com/airlines.htm

Microsoft
Download a free ready made complaint letter about the treatment of an unaccompanied child on a flight, along with templates for many other travel related issues.
http://office.microsoft.com/en-us/templates/CT101467891033.aspx

Missingkids.com
Details the rules that apply when your child is travelling alone with an airline. The site is in PDF format, so you will need Acrobat Reader to view it.
http://www.missingkids.com/download/flying_tips.pdf

WorldWide Classroom
Midway down this page you will find tips on sending children, minors and teenagers abroad on their own safely and legally.
http://www.worldwide.edu/planning_guide/Safety_Traveling_Solo/