Prattle
Prattle is a room-based message-board system written in PHP4. It is built on an organizational model that considers conversations to be topically linear, not threaded. Messages are grouped into discussion rooms, hence the "room-based" reference. Prattle's linear discussion model encourages serious conversations to grow, with continuous give and take, rather than encouraging the short-burnout exchanges that you see in threaded systems. Prattle is not particularly good at, nor is it intended for, question/answer message boards. Prattle uses a MySQL database on backend for data handling.