Deciphering Medspeak (specialized language of health professionals) [Medical Library Association]

Dictionary of Dental Terms

Glossary of Genetic Terms 

Harvard Medical School Family Health Guide

Household Products Database [National Library of Medicine]

Merck Manual for Diagnosis and Therapy

Merck Manual of Medical Information [Home Edition] 

NIH News in Health ["NIH plays a major role in finding better ways to diagnose, treat, cure or prevent diseases. The practical health information in The NIH News in Health is based on research conducted either by NIH's own scientists or by  grantees at universities and medical schools around the country."]

RxList - The Internet Drug Index

A User's Guide to Finding and Evaluating Health Information on the Web [Medical Library Association]