General Shortcuts
Ctrl + S = Save
Ctrl + O = Open
Ctrl + P = Print
Ctrl + C = Copy
Ctrl + X = Cut
Ctrl + V = Paste
Ctrl + N = New Document
Ctrl + '+' = Zoom In
Ctrl + '+' = Zoom Out
Ctrl + Q = Terminate program
Ctrl + W = Closes window (document you're working on)
Ctrl + R = Opens up rulers on the screen for measurement
Ctrl + A = Select All
Ctrl + D = Deselect
Ctrl + Z = Undo once (press again it will re-do)
Ctrl + Alt + Z = Undo (press again it will undo)
Ctrl + Alt + F = Feather
F = Change view of screen
Alt + Shift + Ctrl + K = Change Keyboard Shortcuts
Tools Shortcuts
Q = Quickmask mode (press again to turn off)
W= Wand tool
E = Eraser
R = Smudge Tool
T = Type/Text tool
Y = History brush tool
U = Shape Tool
I = Eyedropper / colour selector tool
O = Dodge / Burn tool
P = Pen tool
A = Path selection tool
S = Clone stamp tool
G = Fill tool
H = Hand tool
J = Red eye tool
K = Slice tool
L = Lasso tool
Z = Magnifier / Zoom tool
C = Crop tool
V = Move tool
B = Brush tool
N = Notes tool
M = Marquee tool
Color Shortcuts
Ctrl + Y = Change document to CMYK
Ctrl + B = Change Colour Balance
Ctrl + M = Change Curves
Ctrl + I = Invert Selection
Ctrl + U = Change Hue/Saturation
Ctrl + L = Change Levels
D = Change foreground colour to black on pallete
X = Switches foreground & background colours on pallete
Layer Shortcuts
Ctrl + Shift + N = New Layer
Ctrl + E = Merge Selected layer down
Ctrl + Shift + E = Merge all layers
Ctrl + J = Duplicate Layer
Ctrl + G = Create new layer group
Ctrl + Alt + G = Create Clipping Mask
Alt + = Select bottom layer
Alt + = Select Top layer
Shape Shortcuts
Ctrl + T = Transform
there is a couple more that i use often..
Shift + any tool's letter to select the next tool of that type
Ctrl + num 0 [on the num pad] to resize to fit
Ctrl + Alt + num 0 to resize to screensize [100%]
Tab to hide all the pallets
Ctrl + shift + S to save as
Ctrl + alt + shift + S to save as for the web
ctrl + alt + shift + E to merge all layers into a new layer.. make sure u have a visible layer selected
Ctrl + F to reapply the last filter
Ctrl + alt + F to reopen the last filter so u can change the settings
Alt + backspace to fill with foreground color
Ctrl + backspace to fill with background color
Shift + backspace to open the fill options
Ctrl + Alt + G for Gaussian blur
Ctrl + Alt + C for clouds
Ctrl + Alt + W to flip horizontally
Ctrl + Alt + E to flip vertically
Ctrl + Alt + R to use the wrap tool