One of my more useful things, cmd+shift+m and cmd+shift+u to minimize all windows and un-minimize all windows of the active application. The un-minimize gets used more often (e.g. I may have a few Chrome windows minimized during my workday that I want to un-minimize en masse after work is done).

    local cmdShift = {'cmd', 'shift'}

    hs.hotkey.bind(cmdShift, 'm', function()
      local app = hs.application.frontmostApplication()

      for _, window in pairs(app:allWindows()) do
        window:minimize()
      end
    end)

    hs.hotkey.bind(cmdShift, 'u', function()
      local app = hs.application.frontmostApplication()

      for _, window in pairs(app:allWindows()) do
        window:unminimize()
      end
    end)