Pidgin-paranoia is a plugin for Pidgin (formerly known as Gaim) that provides information-theoretically secure encrypted conversations using one-time pads. Because the plugin uses a one-time pad where the secret key has the same length as the message and the key is only used once, the encryption is information-theoretically secure. This means that from the encrypted messages the contents of the messages are not revealed. In short: If you use truly random numbers to generate the key files, and if you keep them perfectly secret, one-time pads can not be broken.
Smuxi is an irssi-inspired, flexible, user-friendly, and cross-platform IRC client for sophisticated users. Smuxi is based on the client-server model: The core application (engine) can be placed onto a server which is connected to the Internet around-the-clock; one or more frontends then connect to the core. This allows the connection to IRC to be kept up even when all frontends have been closed. The combination of screen and irssi served as the example for this architecture. Smuxi also supports the regular single application mode. This behaves like a typical IRC client; it doesn't need separate core management and utilizes a local engine that is used by the local frontend client.