TIP: More Layer Mask shortcuts

To create an inverted layer mask (filled with black): Option-click (PC: Alt-click) on the add a mask button
To jump to the layer mask thumbnail: Command Shift backslash (PC: Control Shift backslash)
To load the layer mask as a selection: Command Option Shift backslash (PC: Control Alt Shift backslash)

Copied shamelessly from The Photoshop Channels book by Scott Kelby (now available on amazon or wherever fine books are sold)