Is it possible to close all windows and software without logging out

Sometimes I end up with 8-10 apps open, and dozens of windows all over the place. Then, because it's such a mess, I want to clear everything and start again. But I don't want to log out because I have a dozen or so drives connected, and when I log out they take time to reappear when I log back in, and because I don't need all those drives (most are archive drives), I use an Automator script, inititated on log in, to unmount the drives I don't need.

So, is there a keyboard shortcut where all open windows are shut, and all open software is quit, but without logging out? A sort of "Clear everything and start again".