Here are some links to useful websites:

Scouting
Boy Scouts of America (BSA):  http://www.scouting.org/home.aspx
BSA Grand Canyon Council:  http://www.grandcanyonbsa.org/
Boys' Life magazine:  http://boyslife.org/
Scouting magazine:  http://scoutingmagazine.org/


Space Derby
Construction Guide 1:  http://pack350.homestead.com/Rocket_Construction_Guide.pdf
Construction Guide 2:  http://www.etekgadget.com/SpaceDerbySpaceShipConstruction.htm


Pinewood Derby
Tips from Boys' Life:  http://boyslife.org/hobbies-projects/pinewood-derby/
Tips from Derby Gurus:  http://www.derbygurus.com/uploads/Top_Ten.pdf


Resources
Boy Scout Trail:  http://www.boyscouttrail.com/cub-scouts/cub-scouts.asp