Perhaps require solving a hacker-related "captcha" for submitting stories or posting until your karma has passed a certain threshold. For example, fix a line of code or enter the order of complexity of an algorithm.
Sweet! Then we'd get major practice in for our Google interview as well. Don't forget puzzles involving sparrows, rowboats, candles, and ropes for those of us who might be elsewhere-bound.
people in academic disciplines have known for years that the best way to to get joe public to leave you alone is to make your interests seem really boring.