Aviation for Kids is a site dedicated to everybody interested in Aviation as well as Education, Science, Technology, and Parenting (my son is in most of the pictures and videos).
Since 1992, the EAA Young Eagles Program has dedicated itself to providing one free plane flight for any child who desires it. The Young Eagles is a national program with locations all over the country.
Aviation Activities for Kids has Four fun aviation activities for kids from How Stuff Works including rocket races and a stable airplane mobile.
Create your own flight plan and aeronautical charts with Skyvector. It’s a little tricky at first, but there are plenty of tutorials for budding pilots.
With Aviation Weather Center your can track weather conditions around the world.
The GeoFS website is a free, online flight simulator with visual imagery from around the world.
You can build your own plane with four amazing from-scratch aircraft, plans.
A fun game from the National Museums of Scotland. Build a plane and fly it during a rescue operation in the jungles of Borneo.
This British YouTube series, Amy's Aviation offers the basics of aeronautics. Suitable for children just beginning to explore the mechanics of flight.