There are people who run one or another of the BSDs (stands for Berkeley Software Distribution, a true Unix) on their desktop. I did it, once, until my wife caught on.
Now, there's an organized effort to integrate the KDE desktop environment with BSD and a heap of applications. The selling point is security and performance. The tinkerers among us will no doubt flock to DesktopBSD, at least to give it a trial. (I'm already downloading it, though it's only in the release candidate stage of v1.0.)
Find a review of sorts, here.