TinyIB is a lightweight PHP image board which emulates the functionality of 4chan. If you use MySQL or SQLite, you can use it to create an efficient setup able to handle large amounts of traffic. If you don't use a database, it can store posts as text files for a portable setup capable of running on virtually any PHP host.
Qodem is a re-implementation of the Qmodem DOS shareware communications package, updated for more modern uses. Major features include Unicode support, scrollback buffer, capture file, screen dump, dialing directory, keyboard macros, script support, Xmodem, Ymodem, Zmodem, and Kermit. It can connect over serial port, telnet, ssh, rlogin, and command line, and supports multiple terminal emulations including ANSI.SYS, Avatar, VT100/102, VT220, and Linux.
miniBB is a flat, linear, highly customizable BB. It features MySQL, PostgreSQL, and MSSQL support, table name definitions, color skins, language packs, HTML templates, access control, smilies, search, basic BB codes, member titles and ranks, moderators, email notification, statistics, encrypted cookie logging, IP and user ID tracking and bans, spam protection, "sticky" topics, a powerful admin panel, and more.
KDX is a powerful cross-platform BBS-style encrypted Internet communications system that provides messaging, news, file and folder transfer, voice chat (Internet Telephone), text chat, remote access, trackers, and more. It uses strong encryption to protect communications for security and privacy. It is useful for groups that need to collaborate on a project via the Internet. It is also very useful for remote administration of a computer. It uses a client/server architecture.
Volley is a modular client/server application for chat, file sharing, and so forth. It is similar to Hotline, except its modular design allows for the addition of more services than just the usual chat, files, and news; there could be multiplayer games, and online meeting tools such as virtual whiteboards.
The Faq-O-Matic is a CGI-based system that automates the process of maintaining a FAQ (or Frequently Asked Questions list). It allows visitors to your FAQ to take part in keeping it up-to-date. A permission system also makes it useful as a help-desk application, bug-tracking database, or documentation system.