LibraryBox
From Just Solve the File Format Problem
LibraryBox is a portable, inexpensive WiFi file server which can be assembled by anybody from easily-obtained hardware and free, open-source software. It can be used to cheaply and easily make files available wirelessly to anybody within its range even if Internet access is not available. Some of them were deployed at the 2013 SXSW festival in Austin, Texas.
LibraryBox is actually a (more respectably-named) development of technology originally created as PirateBox.