AskDrWiki.com is a medical encyclopedia based on a wiki platform. The authors were one of the first to use YouTube to upload medical videos. Dean Giustini and I discussed this fact a few weeks ago, and he wrote about it in his landmark BMJ editorial How Web 2.0 is changing medicine, linking to AskDrWiki.com.
Coronary Angiograms: Coronary Dissection
Ganfyd is another medical Wiki community, created in November 2005 by a group of doctors working in the UK. It is intended to become a large on-line textbook of medicine (source: Wikipedia).
Graham shares his concerns about medical wikis in his post "I Will Never Trust Dr. Wiki… because I will never trust malicious teenagers."
Mike Cannon-Brookes has a nice presentation on Organisational Wiki Adoption on SlideShare (link via DavidRothman.net). This may convince your department or hospital to start a wiki, if you do not already have one.
Wikis in Plain English
Do We Need a Free Medical Encyclopedia?
British Medical Journal Features Clinical Cases and Images - Blog, Again
I Will Never Trust Dr. Wiki… Grahamzon.com.
Medical wikis. DavidRothman.net.
Lots More Medical Wikis. DavidRothman.net.