The Intelligere Flash Chat System is a complete chat system based on Flash on the client side and on PHP on back-end. The server used for the syncronitazion and for the streaming is Adobe FMS. Demo http://www.intelligere.info/intelligereFCS/demo.cfm
XMLSocketd is a server written in C++ to be used with the ActionScript class XMLSocket for communication between Flashmovies.
Can be used for chats, whiteboards, etc in conjunction with any serverside script like PHP for authentication and room handling