PB Wiki, is a free wiki site that allows users to make update and share their own wikis.

Taken from pbwiki.com:
"PBwiki is the world's largest provider of hosted business and educational wikis. We host over 400,000 wikis, serve millions of users per month, and 96% of our business users would recommend PBwiki to a friend. Leading companies from AT&T to Wal-Mart, including 1/3 of the Fortune 500, choose PBwiki to help them with knowledge management, collaboration, project management, and a host of other business processes and workflows."