Navigating the CDC website, looking for specific information, is no easy task these days. While looking for something else, however, I stumbled across the CDC's page on hoaxes and rumors. A surprising number of them are related to HIV transmission (the infamous needle in the theater seat, airborne transmission, and so on).
A lot of these hoaxes and rumors are spread by email. If you should receive one of these helpful missives, the CDC has a page devoted to debunking the rumors: CDC Health-Related Hoaxes & Rumors.