An Android app for transferring files via QR codes.
We made this over 24 hours at a hackathon. Amazingly, it works. Don't try doing this: QR codes can barely represent 1KB each, and without any networking, you're left displaying them very slowly in order to give the reader phone time to detect and scan them. If a code is missed, your file will be corrupted.
Still, it works, and we can move just under 10KB/Minute. Works best when there is not too much glare from the sun. Very secure form of communication. In theory works for any kind of file, altough you might have trouble keeping your phones stable enough for long enough to transfer any media files.