Miranda Instant Messenger is a minimalistic, open source instant messaging client for Microsoft Windows that advocates claim adheres strictly to principles of simplicity and efficiency.
Miranda provides a basic client framework and an advanced plugin architecture, and that's about it. Support for various IM protocols and additional features is implemented through optional plugins, some of which come bundled with Miranda by default and the rest of which can be downloaded from the Miranda IM website. This keeps Miranda lean and fast, since you can easily remove features you don't use. There are currently nearly 200 plugins for Miranda.
Protocols supported via plugins include:2000 and has been developed actively ever since. Miranda IM version 0.3.1 was released on August 22, 2003.
While bugfixes and minor features are still being implemented in the 0.x codebase, the developers have announced that the next major release (1.0) will feature a completely rewritten codebase to allow new features and functionality beyond what the current architecture is capable of.