US Census Bureau has been running a campaign to remind people to fill out their census forms. Above, a sign in Metro Center adopts the appearance of a handwritten census form: "When you answer 10 simple questions, you can help our community for the next 10 years."
For more about the census, see the previous post.
P.S. [added April 28, 2010] The campaign to encourage DC census participation has its own posters as well. These posters (below) combine elements from the English and Spanish posters discussed above, compressing "10 questions, 10 minutes" into a single slogan. Eastern Market metro.