I know that this isn't quite in the spirit of what you're talking about, like proving your ID or personal medical records, but since the Federal "Check 21" law was passed a few years ago giving scanned images of paper checks the same legal authority as the original checks, these digital images have zipped back and forth across the country by the tens of thousands per day. So, that's one area of common everyday living where the digital version of a paper document carries the same weight.