A team called "Umbrella.net" (no relation to Umbrella Corp, we hope) has developed a prototype system of Bluetooth umbrellas that facilitate "sudden, striking, and unexpected connections between people in public and urban space" by forming ad-hoc mesh networks when unfurled. As each umbrella is opened and added to the network, it lights as it comes online. Unfortunately, since there's not a whole lot to do when creating ad-hoc networks that aren't connected to the internet, the primary application of the short range networking system is chat.
Short-range, wireless chat. Now if only we could evolve vibrating, fleshy cords in our throats and a set of communicative phonemes, maybe we could run the chat system entirely with bio-generated power over a sonic carrier.
Read - Umbrellas in the Mesh [Unstrung]