There's this super-budget airline in Australia, Tiger Airways, so budget that they skimped on training pilots and got shutdown for some time. Anyway, their web

There's this super-budget airline in Australia, Tiger Airways, so budget that they skimped on training pilots and got shutdown for some time. Anyway, their website at some point had two hidden features: if you tried to book in a group it would charge you more per person (because you're depriving them of "credit card surcharge") AND just checking the price of a certain flight a certain amount of times (showing interest in that flight) would raise the price by some increment for every other customer on the website automatically.