Occupy.here began two years ago as an experiment for the encampment at Zuccotti Park. It was a wifi router hacked to run OpenWrt Linux (an operating system mostly used for computer networking) and a small "captive portal" website. When users joined the wifi network and attempted to load any URL, they were redirected to http://occupy.here. The web software offered up a simple BBS-style message board providing its users with a space to share messages and files.
Unlike most wifi connections, this one wouldn't let you check your Facebook. It was designed to run entirely disconnected from the internet. Only people physically close enough to the router can could reach the local web forum with their mobile phone or laptop. I imagined it becoming a kind of intranet for Occupiers, filtering users by proximity to specifically support the people at the park."
I'm not sure of the inherent security of a such a thing, but at least it's a step in the right direction, and certainly a cool idea for a private network that only exists ethereally in a small zone for only as long as the router is running.