This set of data is just screaming to be turned into an iPhone app .. imagine, you're somewhere in Europe. The GPS figures out where, and gives you a picture (modern-day) to wipe your fingers over .. revealing the WW2-era pic underneath.
For some European cities, this would be killer .. I know a lot of people who are interested in the history of Europe from the perspective of WW2, and this could be quite an intriguing application to develop ..