WebMD.com

A big portal packed with information about health and related issues. A recent redesign introduced a nifty new tool called Symptom Checker, which lets you self-diagnose—sorry, "pinpoint potential conditions"—in seconds by clicking on body parts and selecting from a list of specific complaints (just be sure to check with your doctor for a real diagnosis). The new WebMD Health Manager lets you store your personal medical records online and make them available to doctors. The new Revolution Health portal, which launched in April, has many of these same tools and features, including its own symptom checker (but WebMD's has cool graphics). Other trustworthy sources of information about disease and other health matters: the Medem Leaning Centers, which aggregates top articles from leading medical societies on a wide range of topics, Centers for Disease Control and Prevention and National Institutes of Health.