Note that holding Shift plus any of these will toggle through their associated tool options.
Cmd+F produces a nifty find window that lets you search for any command or layer by name.
Cmd+Shift+N = Create new layer
Cmd+D = Deselect
Cmd+Shift+I = Invert Selection
Cmd+0 will fill the current image to your screen size. Cmd+1 will give you a 1:1 pixel view.
The number keys (on the top of the keyboard and the numpad) adjust opacity. If a tool with opacity control is selected, they adjust the tool’s opacity. If not then they adjust the opacity of the selected layer. Hold shift and tap any of the numbers to specify fill (layers) or flow (brushes).