Here are two excellent examples of Library Wikis I've come across recently:
Library Success: A Best Practices Wiki
Introduction: "Welcome to Library Success: A Best Practices Wiki. This wiki was created to be a one-stop-shop for great ideas for librarians. All over the world, librarians are developing successful programs and doing innovative things with technology that no one outside of their library knows about. There are lots of great blogs out there sharing information about the profession, but there is no one place where all of this information is collected and organized."
Introduction: "LISWiki was established to give the library community a chance to explore the usefulness of Wikis. It is not intended to replace or detract from the Wikipedia library and information science articles (or those in the printed LIS encyclopedias for that matter), but exist as a niche encyclopedia covering library-related issues."