DARPA’s latest tech challenge should make you hesitate to throw out your shredded documents, instead opting for the handy caveman solution of simply burning them. Until DARPA comes up with a way to read ashes as well as messages on shredded paper.
The PDF has long reigned as the universal document, one that can be read by almost any machine anywhere and be formatted to hold various kinds of information: text, charts, graphics, images, etc. But the problem with PDFs (or spreadsheets for that matter) is that they're pretty static--with the exception of a few (admittedly handy) features, they are fixed in what they can do and convey.
Remember when, as a kid, you would pass “top-secret” notes written in lemon juice that your friends could only read in the right light? Well, in light of new nanotechnology research, this now sounds absurdly antiquated, like cave painting in the modern era. Instead, the youth of tomorrow (and adults too) could have the option to communicate via documents that self-erase at a preprogrammed time.