As the election approaches, even the Stanford bookstore is selling action figures depicting Barack Obama and John McCain. Ephemera and artifacts from previous presidential campaigns were the subject of a wonderful 2004 exhibit titled "Get Out the Vote! Campaigning for the U.S. Presidency" (and website) at Cornell University's Department of Special Colletions.
The Museum of the City of New York is currently featuring an exhibit ("Campaigning for President: New York and the American Election") featuring items from the collection of Jordan Wright, a collector of political ephemera who died in June, 2008. Wright's collection is featured in a recent book, Campaigning for President (New York: Smithsonian Books, 2008), which is in Green Library's circulating collection.
For those researching American elections of the 18th and 19th centuries, Stanford users can also search the rich online collection of printed ephemera from the American Antiquarian Society through the database "American Broadsides and Ephemera"