Tons of market controls have been introduced in the 25 years since "Black Monday," when the Dow Jones Industrial Average dropped 23% in a single day, its largest one-day percentage-point drop ever. Yet, markets are still susceptible to large downturns. And while stock prices are riding high right now, post-election, pre-fiscal cliff volatility seems imminent. Here are 10 things to keep in mind, whether you survived '87 or have just read about it.