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.
libnode is a C++ implementation of Node.js. Just like Node.js, libnode provides non-blocking I/O, which enables you to develop scalable Web applications in C++. The memory management of libnode is automatic, based on either shared_ptr or bdw-gc. libnode is good to use on embedded devices because its system resource consumption is lower than Node.js.