I love when I come across examples of data that I would usually discard being used by other scientists in their research. Optical imagery captured at night would be of limited use to me - but I can think of a few practical applications without too much bother if I could see the urban areas in it (urban sprawl, light pollution, thermal band for heat loss, etc). The value of optical imagery captured at night, with no urban areas in it at all was less obvious to me, but some clever folks at Oxford have come up with a collaboration between economists and remote sensers and used satellite imagery and GIS to develop a metric for counting poverty globally based on the number of people living in darkness at night. The famous photo of North Korea between South Korea and China taking from the space shuttle giving one example - the capital, Pyongyang visible as the bright hub in the centre of the darkness.
Note - I have seen this research attributed to both Stanford and Oxford - I picked the Oxford link for this post.