Free, open-source, and distributed communication platform focused on privacy and security.
Fully configurable IRC client.
Program that sends and receives text messages from PC to PC.
Portable version of Skype that allows making audio and video calls, as well as sending instant messages, without the need for installation on Windows.

Client for Twitter to keep you up to date with the latest news without having to enter the Twitter website.
Latest version of this famous mIRC script.