Thanks to Bespacific.com for the link to a fine up-to-date article about medical research on the internet.
The article itself is here. My only criticism of it is that I don't think it covers the British medical sites.
However, in my opinion, if you consider the value of your time, your best bet is to sign up for MDConsult.com, which is not free, but is reasonably priced.
I've recently posted some other Research Links on this blog, some medical, which I rescued from my firm's website when it was redesigned. Law firms don't offer pages and pages of research links on their websites anymore, it seems. It's a pain in the neck to maintain them, as a certain number of the links "go dead" every year. It takes a lot of work to put them together and maintain them, and it is pretty much a thankless task. Also, the reasoning goes, why offer the reader a multitude of paths leading away from your site? With Google and other powerful search engines, directories of research links are arguably obsolete anyway. On the other hand, there are so many websites now that the researcher's problem is more likely to be sorting out the valuable websites from the chaff. So there's value to a guide to doing medical research on the internet. In the end I couldn't bear to just delete all of mine with the old website, so I copied them here, where they will be of continued use to me at least.