While it's a somewhat different focus (more technical as opposed to patient-based), the most successful medical wiki I can think of is http://www.fluwikie.com/

While it's a somewhat different focus (more technical as opposed to patient-based), the most successful medical wiki I can think of is http://www.fluwikie.com/ http://www.fluwikie.com/. As for the latter two of your posts, I would check out the existant support forums for the particular type of cancer you're going to focus on (I say this assuming that some forums or Yahoo! mailing lists exist out there, as they seem to for just about all diseases).