Easydiagnosis.com: EasyDiagnosis provides an instant online analysis of several important medical symptoms in a user-friendly format, and then predicts the most likely conditions responsible.
Medical Library: Vast online resource. Select your symptoms and narrow down the diagnosis.
Medical Pages: Medical Pages is the first UK Health Portal developed and supported by Nationally accredited Medical Specialists
MedicineNet: MedicineNet 100% Doctor produced healthcare information written for you to make informed decisions about your health concerns
Medline Plus medical encyclopaedia: medical encyclopaedia from the US national library of medicine.
My Electronic MD: medical diagnosis and health information site. Is a US site so be careful of some of the terminology, but does have a very easy to use system whereby you describe your symptoms and view possible causes.
NetDoctor.co.uk: Large independent medical resource
Patient UK: uk health portal with health information and links to health related websites
Yourdiagnosis.com: YourDiagnosis is a secure Online Medical Diagnosis system developed by Doctors. It evaluates your medical history together with your current, past and family details including medications and allergies