Not too many people utilize the windows key on their keyboard but it has many shortcuts that can be very effective. Some of the most common ones are below.
Win = Open Start Menu
Win + D = Restore or minimize all open windows
Win + E = Start Windows Explorer
Win + F = Start Find Files/Folders dialog box
Win+ L = Lock computer
Win + M = Minimize all open windows
Win + R = Start Run dialog box
Win + F1 = Start Help Menu and Support Center
Win + Tab = Cycles through all open programs and taskbar buttons. Press ENTER to select.
Win + Ctrl + Tab = Cycle through all open apps/games Taskbar buttons, Tray icons, Start Menu and Quick Launch toolbars (press Right or Left arrows to cycle through Toolbar and Tray items)
Win + Pause/Break = Open 'my computer' properties window.
Win + Shift + M = Restore all open windows
Win + Space = Scroll down one page at a time in Internet Explorer
Win + Back Space = Scroll up one page at a time in Internet Explorer.