There are some businesses that have an unusual problem. They sell commodities that have a value up to a certain point in time, but that value drops to zero after that moment. A classic example is an airline's inventory. The value of an airline seat drops to zero at the moment the check-in closes. The realization of this simple fact changed the way airlines sold seats in the 1980s and 1990s, pumping up revenue significantly. How does this knowledge make you money? Because with the right systems, as time runs out, you can sell off the seat that won't go at full price much cheaper and provided you cover the incremental costs of carrying the passenger, then you are still making extra profit. I bring this up, because it struck me there was a new, more interesting possibility that could easily be made available to push up profits even further. I was buying a railway ticket online and, as you can see, the system generously offered to bump me up to first class for a suitable extra bi...