Seam carving is really cool, not just for the typical application of changing images, but also as a method of fingerprinting images (and the other side, anonymizing them). There are some interesting papers on these use cases via Google scholar [0].

There are a lot of potential businesses that could be built around image fingerprinting. Off the top of my head those include the obvious copyright/IP monitoring, and also more novel ideas like "meme tracking" to observe the propagation of memes across the Internet.

[0] https://scholar.google.co.uk/scholar?hl=en&as_sdt=0%2C5&q=se...