To perform a Spotlight search from a Finder window, press Command–Option–Space bar. Command–Space bar: Show or hide the Spotlight search field.To close all windows of the app, press Option-Command-W. Command-O: Open the selected item, or open a dialog to select a file to open.To minimize all windows of the front app, press Option-Command-M. Command-M: Minimize the front window to the Dock.To view the front app but hide all other apps, press Option-Command-H. Command-H: Hide the windows of the front app.To find the previous occurrence, press Shift-Command-G.

In some apps, you can undo and redo multiple commands. You can then press Shift-Command-Z to Redo, reversing the undo command.