Washington University webpage on osteoporosis and bone physiology - maintained by a professor, educational site.
On-line FRAX® - Fracture Risk Assessment Tool - on-line tools are of limited use. Consult a doctor for a definitive diagnosis. But still interesting.
QFracture Site - learn your QFracture score, an attempt to quantify risk of a bone fracture due to low bone density in the next ten years.
University of Michigan page on Bone Structure - more scientific
National Osteoporosis Foundation
Osteoporosis and Hispanic Women
International Osteoporosis Foundation Latin America
BestBonesForever.gov - A bone health campaign for girls
The Congress created the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) in 1986. It is one of the National Institutes of Health and acts to allocate research funding into osteoporosis (among other issues) and it also disseminates information about bone health.