The award-winning Sugar Learning Platform promotes collaborative learning through Sugar Activities that encourage critical thinking
http://www.sugarlabs.org
Dia is roughly inspired by the commercial Windows program 'Visio', though more geared towards informal diagrams for casual use. It can be used to draw many different kinds of diagrams.
http://live.gnome.org/Dia
Kinovea is free and open source video analysis software for coaches, athletes and medical professionals.
http://www.kinovea.org/en
Use the osmaps.kml file to add ordnance survey map to google earth.
http://www.brock-family.org/gavin/google-earth/osmaps.html
