This is yet another idea you mentioned that is not well executed due to the profit motive. From Lifehacker:
Web service eSnailer's out to bring back snail mail: eSnailer prints, envelops, stamps, and mails actual dead-tree letters free of charge within 24 hours. You enter the recipient's mailing information, your return address and compose your letter using a rich text editor and send it off all at eSnailer. The catch: eSnailer forces (yes, forces) you to "sign up" for a special offer, using the information entered in the return address. Your call on whether or not the extra "special offer"/junk mail's worth it.