An anonymous reader writes: "Young people, when choosing a profession, are often told to 'do what you love.' That's why we have experts in such abstruse fields as medieval gymel. But let's talk hypotheticals: if there's a worldwide catastrophe in which civilization is interrupted, somebody specializing in gymel wouldn't provide much use to fellow survivors. In a post-apocalypse world, medical doctors would be useful, as would most scientists and engineers. The bad news for Slashdotters is that decades without computers would render computer science and related professions useless. What do you consider to be the most useful and mostly useless post-apocalypse professions? How long would it take for society to rebuild enough for your profession to be useful?"