I'm currently putting together a data recorder for an academic experiment. It requires: GPS, Camera, Environmental data, inclinometer, and a few other odd bits. I could build up a custom system, but that is a big NRE expense for something that less than ten of will probably ever be produced. I could also use a "better" but less common developer board, but that path has its own problems. The experimenter could have stuck with a COTS solution, but the reason that I'm working on it now is the inconvenience and poor quality of the current implementation (lots of COTS stuff bodged together). Currently, they are using a lot of COTS stuff, and then putting the data together in batches. Even though it is a somewhat automated process, it remains slow, labor-intensive, tedious, fragile, etc. When I am done, I get to hand off an integrated, fully automated system that is flexible, built with easily replaceable parts, and best of all; due to the abundance of freely shared examples and documents, a grad student, or even an ambitious undergrad can take over and manage or even customize the system. Also, the rPi based system is much cheaper than the current system.

So, there is one pretty good use for an rPi.