http://www.modimes.org/healthlibrary2/factsheets/Achondroplasia.htm
This fact sheet from the March of Dimes presents the cause of achondroplasia. There is a discussion of its signs and some research being done on the condition. Finally, the site lists a few additional places where one can go to learn about achondroplasia.

http://www.sciam.com/1998/0998issue/0998white.html
This is an article from Scientific American which discusses weightlessness. The last section of the article illuminates the changes in bone density that take place as a result of space flight. Some of the terms have links so that, if you are interested, you can delve into certain topics more deeply.

http://www.osteo.org/osteolinks.html
This site has links to many others related to osteoporosis. Among the topics it covers are: smoking, pregnancy, the relationship to lactose intolerance, and osteoporosis in men.

http://www.osteo.org/pdisbone.html
Paget disease is a rare condition causing malformation and weakness of the bone. This fact sheet briefly discusses diagnosis, treatments, and consequences of the disease.

http://www.oif.org/tier2/fastfact.htm
Osteogenesis imperfecta is due to a problem in appropriately producing collagen. This fact sheet discusses the causes and consequences of the condition

http://imsdd.meb.uni-bonn.de/cancernet/600626.html
This site provides information about several different types of bone cancer. It includes questions and answers about bone cancer and some links.