Planetfeedback.com? You can actually write a letter through that service and if you opt for them to e-mail that letter, the site will often disclose the e-mail address and/or contact info of those execs. Also, you could always google the company and go to their website. Usually, there's exec info within the website, including e-mails, addresses, names, faxes, etc of the execs. Often I'll google the exec name and will find the contact info that way.
