WING is described as 'open-source Wireless Mesh Networking platform aimed at hobbyists and enthusiasts'. There are more than 10 alternatives to WING for a variety of platforms, including Linux, Mac, Windows, OpenWrt and BSD. The best alternative is GNUnet, which is both free and Open Source. Other great apps like WING are cjdns (Free, Open Source), Freelan (Free, Open Source), LibreMesh (Free) and telehash (Free, Open Source).
SMesh is a seamless wireless mesh network being developed by the Distributed System and Networks Lab at Johns Hopkins University. It provides peer-to-peer connectivity, Internet connectivity, and fast handoff to mobile clients across the mesh.