When you Control-click (Macintosh) or click with the right mouse button (Windows), Photoshop displays a context-sensitive menu that changes depending on what tool you have selected in the Tool palette. We find the menu for the various painting tools pretty useless (though if you had to do a lot of painting, it might be helpful). But the menus you get when you Control-click (or right-mouse-button-click) with the Move tool and the selection tools are great.
The context-sensitive menu for the Move tool lets you choose a layer to work on. If you have four layers in an image, and three of them overlap in one particular area, you can Control-click (or right-mouse-button-click) on that area and Photoshop asks you which of the three layers you want to jump to. (Note that you can always get the Move tool’s context-sensitive menu by Command-Control-clicking or, on Windows, clicking the right mouse button with the Control key held down.) The context-sensitive menu for the Marquee tool contains a veritable mish-mosh of features, including Delete Layer, Duplicate Layer, Load Selection, Reselect, and Color Range (we have no idea why they picked these and left other features out). Many of these features don’t have keyboard shortcuts, so this menu is the fastest way to perform them.