The original trolley problem, developed by philosopher Philippa Foot, is straightforward but complex: you can do nothing and let the trolley run over five people or switch the tracks and kill one person.
Neal Argawal, a maker of silly and fun online games, offers a long series of variations of the trolley problem. For example, would you save one cat or five lobsters? Would you kill one stranger or five clones of yourself? Five elderly people or one baby? The answers are rarely obvious, as this example demonstrates. I'd hate this one in particular because it would require me to do math under pressure.
-via Flowing Data