You might want to check out Confluence, as it is likely the leading enterprise wiki on the market. There is a SharePoint Connector for that wiki as well. As one of the contributors to the SharePoint Connector I am a little biased, but you are probably doing yourself a disservice if you don't check out a few of the options that are out there. Wikis can be powerful and contagious, but this won't happen if the wiki is sub-par.
