Once upon a time, before people's ears grew cell-phones and their hands grew blackberries, before stock-market orders were filled electronically in less than a second or the commission was waived, ordinary mortals who wished to dabble in stocks or options did so by phoning a real person, commonly (but erroneously) known as a "broker", who wrote the requested order on a paper form and relayed it via an "order desk" to a real "floor trader", who arranged...