Forumtalk

Forumtalk is the collective name for an Apache module and a server which, together, can be used to create high performance Web forums. The Apache module allows for special Forumtalk-tags to be placed within HTML templates which will be replaced by forum data. Currently, the server can store its data in a MySQL or a PostgreSQL database. Communication between the forum server and the Apache module is in XML, which makes it possible to easily extend Forumtalk with new clients.

http://www.forumtalk.org