I hang mine around my neck like Flavor Flav. Then I put the logos in all my emails and letter head. And I have copies in different frames, next to pictures of me, through out my office and house. Depending on the conversation I start every sentance with "As a (Insert cert here - CISSP - CHFI, Sec+ETC) I see it like this...."
Ok I lied. I really have no idea what happened to them after they came in the mail.
CISSP, C|HFI, Security+, Network+, XYZ...blah.