The major credit bureaus have the right to sell your personal information to credit card and insurance companies, resulting in the deluge of junk mail. But you have the right to exclude your name from preapproval lists (either permanently or for a 5-year period). To do so, call the automated number 1-888-5-OPTOUT, or go online at OptOutPrescreen. It only takes 10 seconds to protect your privacy and save a few trees!
UPDATE: I’ve received some inquiries about whether this is legitimate, or just yet another scam to get you to give someone your personal inforamtion. (Good! We need to be skeptical of such requests!) Rest assured, this is a service required by law, and mentioned at the Electronic Privacy Information Center’s website (highly recommended site, btw), the Michigan Attorney General’s site, and, most importantly, the Federal Trade Commission. Most of these sites list the toll-free number only, but when you call the number, they reference the website as well.