Now this is a neat idea for this years Digitalks, Barcamp, … season:
PirateBox is a self-contained mobile communication and file sharing device. Simply turn it on to transform any space into a free and open communications and file sharing network.
The PirateBox consists of a wireless router and light-weight Linux server connected to a USB hard drive. The system can run on AC or DC power which allows it to be fully mobile. You can take it to the park, operate it a cafe, in a subway, at work, etc.
The PirateBox is registered under the Free Art License (FAL 1.3). It can be built for approximately US $100. For detailed instructions, visit the PirateBox DIY page.