ADP Forum is a discussion board system that doesn't use any database, but instead stores all the data in txt files. The forum is highly customizable, you can easily edit: colours, fonts, icons. There is a detailed readme file that explains how to install. It features: user authentication, member ratings, avatars, configuration panel, administration, email notifications, smiley option, edit and delete options. Languages available: English, Italian, French, Spanish, Swedish, Polish, Finnish, Norwegian, Slovakian, Bosnian.
PHP/MySQL-based board that runs very stable extremly fast even on large sites like www.thewall.de/forum/. Features: MySQL Support, usergroups, private messaging, news backend with comment function, avatars, statistics, multilingual installer, highly customizable with themes and hacks.
An easy to use, and easy to install forum application. Visitors don't have to register, but can enter an username and password to edit their posts. You can configure forums to be validated, meaning each new topic (not new reply's) has to be validated by the webmaster/admin.
ProZone is a fast, feature-packed message board system that is easy to install, use and moderate. One master admin can moderate all threads and change settings. The Master Admin can make unlimited extra admins for single or more threads.
The Talkboard Forum tries to mix the good features of other forums and its own ideas. It uses a MySQL database and extended classes, like templates. Specials are publickey authentication, virtual linking of threads and enhanced banning capabilities.
SmartBB is a PHP bulletin board system which allows webmasters to create an online community with ease. The whole project right from design down to the coding has been specially adapted to suit both a small communities needs and also the larger commercial sites. Comes with 3 administration areas for complete control of your forum and its design. Permissions allow complete configuration and control over the board and its members. Many other features such as language packs, skins and PM.