SteamCache.Net is a system for caching Steam game downloads so that multiple computers on the same network can more quickly install games.
The primary use case is gaming events, such as LAN parties, which need to be able to cope with hundreds or thousands of computers receiving an unannounced patch – without spending a fortune on internet connectivity. Other uses include smaller networks, such as Internet Cafes and home networks, where new games are regularly installed on multiple computers; or multiple independent operating systems on the same computer.