My friend Collin Bode and I were sitting around one afternoon bouncing ideas around & through a lemonade and a beer. The big idea came up to create MapWiki. The name says it all. I realized later others have done this. (e.g. http://www.citeulike.org/user/ianturton/article/559523).
We specifically wanted something that could integrate well with natural history collections databases and also include spatial certainty, linking back to source specimen records, and a registry of organizations and names.
Anyway, a rough prototype lives at: http://mapwiki.berkeley.edu/