Short-Cuts: Photoshop

cmd+Z  = undo

cmd+X  = cut

cmd+C  = copy

cmd+V  = paste

cmd+N  = new document

cmd+P  = print

cmd+A  = select all

cmd+S  = save

cmd+shift+S  = save as

cmd+shift+opt+S  = save for web and devices

cmd+; = visable guides/invisible

brush+[ = smaller brush diameter

brush+] = larger brush diameter

brush + shift = paint in straight line

brush + opt = eyedropper tool

spacebar = hand tool

Z = zoom tool

option + mouse scroll ball up and down = zoom in and out

move tool + opt = duplicate image on new layer