Just saw this and thought it was worth sharing.
Can you guess what this picture shows?
The "thing" next to the fingernail is a functioning computer created at the University of Michigan (and it measures just .3 mm a side). It's run by photovoltaics and is primarily used as a precision temperature sensor. The caveat is that once it loses power, it loses all prior programming and data.
It tests the limits of what we call a computer - but it's multitudes better than the previous iteration, and innovation breeds innovation.
Exciting stuff!