7th BBS: A modular Bulletin Board System based on PHP 5 and MySQL 4+. [Open source, GPL]
aterr: An open-source, web-based, threaded forum system written in PHP, supporting nested posts and forums.
Bestweb: Usenet style threaded discussion, multiple forums, multiple languages, automatic archiving, printable pages, and message voting.
bSpeak Threaded Messageboard: A PHP and MySQL based messageboard software. [Commercial]
ccForum: A simple, easy to use message board system. It supports single or multiple forums, user registration and anonymous posting, and forum administrators. ccForum is written in PHP and is based on a MySQL database. [Open source, GPL]
ClanWeb: The official forum for the ClanWeb application.
DCForum+: A PHP/MySQL implementation of DCForum web discussion program. [Commercial]
Dynamic Flash Forum: A PHP and MySQL based message board with animated and easy to use Flash interface. [Open source, GPL]
ezPhpForum: A simple to use PHP forum package.
FUD Forum: Very feature-rich PHP forum system with MySQL/PostgreSQL backend
FunkBoard: A multi-thread customisablebulletin board messaging system. It uses PHP and either MySQL or PostgreSQL database. [Freeware]
IbPhp: Ikonboard's PHP version. It supports all CGI version's features and it's free. A free registration is required to download the script.
IceBB: Open-source forum software in PHP.
k4 Bulletin Board: Downloads, modifications, news and general information. [Open source, MIT/X Consortium License]
LiteBoards: A discussion forum/messageboards software. [Open source]
MBoard: A simple message board for those who don't want or need large forums. Supports smileys, e-mail notification and more. [Freeware]
MercuryBoard: Bulletin board written in object-oriented PHP4 with a MySQL database backend.
miniBB: Small, fast and free discussion board system written in PHP, can be based on any database supported by PHP (including mySQL and PostgreSQL).
myBB: Coded in PHP and backed by mySQL. Free
Oneiric Bulletin Board: Oneiric is a free (GNU/GPL) PHP Bulletin Board with a mySQL backend.
OvBB: A light-weight and fast bulletin board system that mimics vBulletin 2 in both look and behavior while incorporating new features and functionality. [Open source, MIT]
Oxygen: A highly customisable open-source web-based bulletin board that requires PHP4, a mySQL database.
Phorum: A free threaded, web-based bulletin board system written in PHP with a variety of backend database option available.
PHP/XML Forum: A free thread-oriented, XML-based news forum. No database required.
phpNet: A feature enriched PHP/MySQL message board.
Prattle: A message board system implementing a clean linear model. [Open source, GPL]
ProBB: ProBB is a web bulletin board written in PHP and backed by several databases, including MySQL, MsSQL, and PostgreSQL.
PunBB: Lightweight PHP discussion board with MySQL/PostgreSQL database backend
SEO-Board: A fast, and search engine friendly forum software written in PHP/MySQL. [Open source]
SkaidonDesigns: phpBB, vBulletin, IPB templates.
SMF: A community software package with themes, fast message database, secure file-attaching system, and mod installation manager. [Freeware]
SowiBB: Forum software written in PHP with a MySQL backend.
Supermod: A PHP forum software to a higher level YABBSE based concept radically modified and customized for free.
TinyPHPForum: An open source PHP-based database-free very small and simple forum with Multi-language, multi-skin, avatar uploading support.
Transverse Styles: Provides Invision Power Board skins and vBulletin styles. All skins and styles are packaged with fixed and fluid configurations. [Commercial]
tribbyBoard: A free threaded message board script written in PHP with a MySQL backend.
UBBThreads: Threaded or linear viewing of posts, address books, CSS compatible, member list, time offsets, session or cookie based, moderators, multi-language support, private forums, profanity filter, and user pictures. [Commercial]
UseBB: A PHP/MySQL bulletin board package designed for small to medium sized web sites. [Open source, GPL]
vtiger Forums: An easy-to-use and scaleable open source bulletin board system that enables you to easily create, manage, and promote your online community.
W-Agora: Free forum written in PHP. It has also a guestbook, a download area, a photo gallery and a news publisher feature. It uses MySql as database.
WiForums: Interoperable (vBulletin, phpBB2 and IPB) Web/WAP Discussion Forums for Cell phones, PDAs and other handheld devices.
WMForum: A very simple discussion board program written in PHP. It doesn't use any SQL database.
WowBB: WowBB offers features such as auto install/upgrade, a WYSIWYG editor with integrated spell-checker, auto time zone detection and smart caching. Requires PHP and MySQL.
WSN Forum: Fully customizable, extensible and translateable PHP/MySQL forum script. [Commercial]
Xsorbit: Free forums and professional message board and forum software for personal or business use.
YaBB SE: A PHP/MySQL port of Yet another Bulletin Board (YaBB) 1 Gold (see above).
YapBoard: A simple PHP/MySQL message board.