Get a free Smithsonian magazine subscription. Just fill in the requested information and take their short survey. You do have to refer a friend, but I just used a different freebie finding email.
From their site: Smithsonian magazine is a monthly magazine created for modern, well-rounded individuals with diverse interests. It chronicles the arts, history, sciences and popular culture of the times. Each subscription includes a complimentary membership to the Smithsonian Institution.