MedHelp
MedHelp is an online health community that claims to be the largest in the world, with over 12 million monthly visitors.
MedHelp members can create Personal Health Records (PHRs) and use condition-specific applications. MedHelp offers over 1500 symptoms and treatments to track with over 5 million data points collected to date.
MedHelp has information about diseases and drugs, advice on healthy living, Ask an Expert (including veterinarians) forums, and a Doctor Finder.