http://twiki.org/

Overview:
TWiki is a flexible, powerful, and easy to use enterprise collaboration platform. It is a Structured Wiki, typically used to run a project development space, a document management system, a knowledge base, or any other groupware tool, on an intranet or on the internet. Web content can be created collaboratively by using just a browser. Users without programming skills can create web applications. Developers can extend the functionality of TWiki with Plugins. Administrators can tailor their TWiki installation with over 300 Plugins and add-ons available from TWiki.org.

Deployment:
TWiki is the most popular wiki used behind corporate firewall; it gets downloaded more than 10,000 times a month and is in use by the majority of Fortune 500 companies. Some TWiki deployments behind corporate firewall have over 100,000 pages and more than 15,000 registered users.

Features/Extensibility:
TWiki can be extended with features not found in plain wikis, such as action tracking, barcode generation, blogging, calendaring, charting, conditional text, database access, Extreme Programming tracking, global search & replace, image gallery, LaTeX support, mail into wiki pages, page hierarchy, platform to build wiki applications, slideshow presentations, spreadsheet calculations, table editor, tagging, web form handling and reporting (with TWikiForms and FormattedSearch), word alias support, XML and XSL transformations, and more.

Competing Products:
Confluence, Socialtext, TWiki ==> compare them

Support:
TWiki is an open source project. Administrators can get free support in the Support web and at #twiki IRC. Many consultants, such as StructuredWikis LLC are available to install/customize/support TWiki, and to create custom wiki applications.

Management:
Peter Thoeny
TWiki Open Source Community

Customers:
More than 40,000 organizations worldwide, including Adobe Systems, Airbus, Alcatel, Agilent Technologies, Amazon.com, AMD, AT&T, Boeing Satellite Systems, British Telecom, Broadcom Corporation, Cisco Systems, Deutsche Bank, DHL, Disney, Dresdner Kleinwort, eBay, Ericsson, Fedex, GE, Google, Hitachi Data Systems, HP, IBM, ILOG, Intel, Lucent, Lufthansa, Mentor Graphics, Michelin China, Motorola, Nokia, Nortel Networks, Northrop Grumman, Novell, Oracle, PayPal, Reuters, Raytheon, SAP, Siemens, Sun Microsystems, Symantec, Texas Intruments, UBS AG, WIPRO, Yahoo!