Syncless is an experimental, lightweight, non-blocking (asynchronous) client and server socket network communication library implemented in Stackless Python 2.6. It contains an asynchronous DNS resolver (using dnspython) and an HTTP server capable of serving WSGI applications. It aims to be a coroutine-based alternative of event-driven networking engines (such as Twisted and FriendFeed's Tornado). It is already about that fast, but it has fewer features and is less stable now.
IRC-API is a stateful, asynchronous IRC API written in Java. It offers an (a)synchronous programming model to its user, and has the ability to save the IRC server state per IRC connection. It supports SSL. The API has been tested on various IRC networks, including EFnet, DALnet, and Undernet. It offers a useful, detailed interface to the Server it connects to.