phpBB

From the official phpBB website:

Since its creation in 2000, phpBB™ has become the most widely used Open Source forum solution. Like its predecessors, phpBB™ 3.0 "Olympus" has an easy to use administration panel and a user friendly installation process, which allows you to have a forum set up in minutes.

With a large and highly customisable set of key features coupled with a standards compliant interface, phpBB™ will grow with, and compliment your website. With millions of installations worldwide, it is no wonder phpBB™ is one of the most popular ways to create and support a community.

To learn more about WordPress you can visit the official website here: http://www.phpbb.com/

Wallanet has set up a demo version of phpBB so you can try it out. We've included access to the admin interface as well.

The demo version can be found here: phpBB Demo

You can login to the admin panel for this package by going here:
phpBB Demo Admin
Username: demo
Password: demo

To learn more about this forum and all the other forum packages that Wallanet offers go here: http://www.wallanet.com/open_source_packages/forums