If the Web's most powerful images are the ones that go viral, then Erik Martin oversees the most infectious petri dish around. Martin, 33, is the general manager of Reddit, a website whose users submit items and then vote the entries up or down, creating an ever shifting news-popularity tote board. Since its founding in 2005, the site has avoided the influence of corporate brands and self-promoting celebrities, instead favoring the sometimes questionable taste du jour of its hive mind. As Reddit has matured (the site hit 28 million unique monthly visitors last fall) its users have mellowed, even taking up a few altruistic causes along the way. But the next time you find yourself watching a video of a reporter swallowing a fly, you can guess that Reddit probably had something to do with it.