Time Traveler Essentials
This is quite simply brilliant: a cheat sheet for mad scientists to hang in their time machines so that they can fundamentally rebuild civilisation (or at least make serious amounts of money) if they end up stranded back in the past. Have to admit to thinking about this in the past, probably as a result of a boyhood collision with some L Sprague de Camp book or other, so there's definitely a market for it!
Would presumably also work in advent of nuclear war, asteroid impact, or any other chance to rebuild civilisation. Nifty
TopatoCo: Time Traveler Essentials Print