Apperceive

wikipatterns.com is a fantastic site that collects both best and worst practices around wiki's. There is some really spot-on information here that many people have found out through experience. Socailtext also has a Best Practices wiki and there are others, but wikipatterns brings it all together in one attractive place (is that a pattern? Maybe we should call it CoolSite).

There are a number of other excellent resource pages. In particular, I found a very useful list of articles about adoption of Web 2.0 technologies into the enterprise.

Cool badge and Creative Commons license too :)

Here's a snapshot of the home page:

Not sure what a wiki is? Check out this video from PBWiki: