I LOVE shortcuts! Here are the ones I use a lot (In PSE)
CTRL+Z = UNDO!!! I use that one A LOT! lol
CTRL+Y = Redo
CTRL+U = Adjust hue/saturation window (for recoloring)
CTRL+G = Clipping mask (clips selected layer to layer below it)
CTRL+E = Merge (when only one layer is selcted, it will merge with the layer below it... more than one layer selected, merges all those layers)
CTRL+N = New Canvas
SHIFT+CTRL+N = New layer
CTRL+J = Duplicate layer
SHIFT+CTRL+J = New layer via cut (after selecting part of an element, usually use the lasso tool to select a piece and want it on its own layer)
CTRL++ = Zoom in
CTRL+- = Zoom out
CTRL+D = Deselect (usually when I've used the magic wand tool to select something... deselects the "dancing lines".... lol)
CTRL+] = Bring forward
CTRL+SHIFT+] = Bring to front
CTRL+[ = Send backward
CTRL+SHIFT+[ = Send to back
CTRL+S = Save
CTRL+SHIFT+S = Save as