clipped from: consumerist.com If you call and reach an operator, using a line like, "I'm updating my boss' contact list and I wanted to make sure I had the most current information for so-and-so," can get you far. Sure, it's a little dishonest, but it's a pretty reliable tactic.
Try finding an email address that shows the format of the company's email addresses. i.e. firstname.lastname@business.com. Often times you'll find this on press releases where company publicists will list their contact info. Try fitting the CEO's name into that email format and sending off an email to them. Sometimes companies will change the format of their executive's email addresses, but more often than not, this will work.
If you call after business hours, sometimes the company will have an automated directory that you might be able to navigate to get through to leave the CEO a message.