Alex Miller gives an excellent example on how to make rock-paper-scissors with core.async which made me want to try it on my mekanikmaskin - a computer-aided learning and examinating tool.
The cool thing about core.async is that it makes sort-of a reactive programming possible. Put something in a channel, and watch the program take care of it. Almost like REPLs waiting inside functions wherever you like.
And yes, it's a terrible mixture between printlns and the async constructs, but the way to create a more advanced interaction is for another day.