PetaPixel has a series of Dutch historian Jo Teeuwisse's photos on display. Teeuwisse seamlessly blends old World War II photos of soldiers into those of the same locations in modern France.
Teeuwisse began shooting her then-and-now photos after finding 300 old WWII photographs on negatives at a flea market in her hometown. After having the images digitized, she visited the various locations shown in the photos (figuring that out is a feat in its own right) and re-photographed them from the same location and with the same framing. The two versions are then combined with careful blending in Photoshop.Go to PetaPixel to see more. There are links to Teeuwisse's work there also, which is all under copyright. (The photo above is just a sample to get you to go look ...)
Via Joseph Susanka.