Repositions marquee or shape while selecting or drawing

Any marquee tool + spacebar + drag

Adds to or subtracts from selection

Any selection tool + or Alt + drag

Intersects a selection

Any selection tool + + Alt + drag

Constrains marquee or shape to square or circle

+ drag

Draws marquee or shape from center

Alt + drag

Constrains shape and draws marquee from center

+ Alt + drag

Ctrl (except when or any shape tool is selected)

Switches from to

Alt + drag

Switches from to

Alt + click

Moves copy of selection or shape

+ Alt + drag selection

Moves selection area or shape 1 pixel

Any selection + ^*

Moves selection, shape, or layer 1 pixel

+ ^*

Moves layer 1 pixel when nothing selected on layer

Ctrl + ^*

Increases or decreases detection width

+ [ or ]

Accepts cropping or exits cropping

+ Enter or Esc