Here's a non exhaustive but typical list of Cocoon use-cases, including some weird ones to show Cocoon's flexiblity...

- Convert XML documents to HTML for publishing
- Generate the presentation and navigation aspects of web sites
- Generate HTML, PDF, RTF documents and images off-line
- Acquire XML data over network connections, process and redistribute it
- Act as a front-end for SOAP or XML-RPC backend components
- Implement a complex HTML forms-based application which saves data in XML
- Build a query and navigation front-end for a relational or XML database
- Generate customized HTML pages depending on the type of client: different browsers, mobile devices, etc.
- Dynamically generate images out of XML data
- Generate MIDI music files from SAP data
- Convert structured text files to XML and HTML
- Build a secure authentication-based web site
- Build a multi-language website using XML dictionaries to translate menus and messages
- Build web portals using the latest JSR-168 standard
- Write web applications with little code and no state management code using the Flow subsystem
- Allow Java objects to be edited from a WAP device

The combination of components available in Cocoon applies to widely varied types of applications. This explains why more and more companies are making Cocoon a strategic component of their toolset.

See also the list of Cocoon features at http://cocoon.apache.org/2.1/features.html