as another example of stuff in go, there is a window-manager called "wingo" that is still pretty alpha, but kinda-sorta-works https://github.com/BurntSushi/wingo
Hey man, I've been running it for at least week for day-to-day work and it hasn't crashed yet. :-)
I'm quite pleased that most of the bugs reported so far are related to state transition bugs, which is the part of Wingo I'm least happy with.
And this includes using completely untested libraries that implement the entire X client stack (from the wire to the screen) in pure Go. Which amounts to roughly 31,000 lines of code.
N.B. I blame Go (mostly) for this state of affairs.