Wiki Loves Monuments: "World's largest photo contest" seeks to create a visual record of world monuments and historic sites on the Wikimedia Commons. The USA version focuses on sites listed on the National Register of Historic Places. Canadian version here. If you don't see your country among the 30 participating so far, you can volunteer!
The Titanic Guide to New York City. An exploration of traces of the disaster, revealing history still written on the landscape.
Photomontage timeline, 1850-2007. Spirit photography, trick photography, comic montages, Photoshop, etc. [more inside]
Voice Thread Now the online world can lend support in your family argument about what really happened on your fifth birthday.