Andrew Loomis made a series of drawings to illustrate the body, different ages, proportions, etc.
You can download some of his books here:
http://www.scribd.com/doc/255814/Andrew-Loomis-Figure-Drawing?autodown=pdfCheck p. 56 for positioning using stick figures to illustrate motion.
http://www.scribd.com/doc/4943407/Drawing-GuideIf you like animals, this might be interesting:
http://www.scribd.com/doc/2435310/-Ken-Hultgren-The-Art-of-Animal-DrawingAnother site with lots of links for doll sculpting.
http://www.dolldesigns.com/tips.htmlChildren:
http://www.dace.co.uk/proportion_child.htm