PhareRougeGL is an Hotline Client/server clone.
Original project:
http://pharerouge.sourceforge.net/
GL version adds more features to be compatible with GLoarbLine server, and 1.9x servers.
GNU/Linux-compatible version of the now unavailable Red Light Variety Alpha software, a Hotline protocol client and server with Japanese language support. Future versions aim at more internationalization and better sharing functions.
Volley is a client/server system similar to Hotline, but using a plugin design that makes it more extensible. Server plugins define services such as chat and file sharing. Client plugins allow users to interact with each other using those services.
hotwired is a Hotline server for Unix-like operating systems. It aims to implement all the features of the level 2 Hotline protocol (i.e. Hotline > 1.5), including transfer queues, threaded news, and user management.