It would be nice with more refined diagnosis tools on the net tho; easily accessible and structured decision trees which can guide you through how to both rule in and rule out possibilities would make a good tool for both patients and doctors. Done correctly it could even cut down unnecessary doctors visits and/or increase chances of early discovery of some diseases.
The NHS has already produced a pretty good one. They also have a really good selection of information on their NHS Direct site, and a local rate national helpline to talk about general health related issues. Slightly more geekily, they have a Behind the headlines news site which gives the real science behind some of the more heinously bad medical reporting that some sections of the media engage in.
Plenty of controversy over nationalised healthcare systems: can't fault the NHS's online presence though, it's a real anomaly amongst Governmental efforts on the 'net.