VuohiMatik is a BBS software designed with large BBS systems in mind. It has filearea operations which work well on tens of thousands of files online, giving the end-user a uniform interface to perform quick selections and searches on the fileareas using various search conditions. Otherwise, it provides similar capabilities to AmiExpress and DayDream.
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.
PsyPoster Message Board is a small yet robust message board made from scratch in Perl. It was designed to replace Matt's WWWBoard by giving users the look, feel, and functionality they wanted out of a message board. It has scaling support for topics, dynamic pages w/headers and footers, and is secured to prevent misuse.
PBLang is a versatile flat file BBS, requiring only PHP 4.02 support. It has a wide range of user specific settings, various skins/layouts, configurable forums, moderators, email notifications, several levels of restrictions, membership groups, a completely configurable layout, sortable members list, avatars, etc. The emphasis is on configurability and reliability.