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.
librouteros is a library that can be used to communicate with devices running RouterOS, a Linux-based operating system by MikroTik. A generic and low-level interface is provided to issue arbitrary commands to the device and receive replies. For some commands, high-level abstractions are provided to simplify communication. The library is thread-safe and reentrant-safe.
libjson is a JSON parser and printer that is fully compliant with the JSON spec. The parser is efficient and interruptible with a simple and flexible API. It also optionally supports extensions like C-style comments or Python/YAML style comments, and for security allows the user to set a limit on the number of nested structures and the parse buffer. The library plugs easily into any model since it doesn't include any object model, and plugs easily in any project's memory management since the memory functions can be redefined.