XNIO is a simplified low-level I/O layer which can be used anywhere you are using NIO today. It frees you from the hassle of dealing with Selectors and the lack of NIO support for multicast sockets and non-socket I/O such as serial ports, while still maintaining all the capabilities present in NIO. Also, XNIO vastly simplifies implementation of channels, opening the door to supporting higer-level transport concepts (like SSL or virtual channels) with the same simple API.
This is the main Wiki page for the XNIO project. The project web page can be found at this location.