Affiche pour le "Papier à cigarettes Job," 1889
I geek out regularly on the New York Public Library's Digital Gallery. You could waste hours on this site. They have uploaded photos and info from their massive collections, such as Walt Whitman manuscripts, vintage holiday postcards, photos of social rights activism and an archive of American menus from 1851 to 1930. I love looking through the turn-of-the-century posters. Plus, it's safer to have up than Facebook if your boss walks by.
The Columbus Metropolitan site has some hometown digital distractions. Not as many as NYPL, of course, but they're worth checking out.