4 years later, i still haven't had a good use for any of these boards, of which i got 6 in total.
I tried making a cluster out of 4 of them, but it gets outclassed by a single second-hand PC cheaper than one Pi.
I have tried using them in robotics projects, since these things can take a standard webcam over USB, which is MUCH easier than an uC with a special camera, but it never really went anywhere.
One of them spent a few years as an always-on home server, but saw almost no use over the time.
All in all, they haven't seen much non-theoretical use here.