Anca is a H.323 client for Qt 3.x. It means that it allows communicating (voice/video) with other similar clients over internet, eg. Gnomemeeting. Its design is minimalist and clean; has a support for embedded devices. It is very modular.
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.
This is a simple IRC-client that was originaly intended as a replacement for winpopup on a local network. It differs from many other IRC-clients in its design. The design of this program is more like the design of the regular peer to peer message managers