cmd: Command Key key | shift: Shift Key key | opt: Option Key key | ctrl: Control Key key

ShortcutDescription
 General
cmd-WClose Window (does not quit program)
cmd-QQuit Program
cmd-CCopy
cmd-XCut
cmd-VPaste
cmd-NNew Document / New Window
cmd-OOpen File
cmd-SSave
shift-cmd-SSave As…
cmd-PPrint
cmd-ZUndo
shift-cmd-ZRedo
cmd-ASelect All
cmd-FFind
cmd-GFind Next
shift-cmd-GFind Previous
cmd-, (cmd-comma)Preferences
cmd-HHide – hides current program
shift-cmd-HHide Others – hides all other programs
cmd-+Make Text Bigger
cmd–Make Text Smaller
cmd-0 (cmd-zero)Revert to original text size
cmd-?Help
cmd-MMinimize Window to the Dock
ctrl-opt-cmd-8Reverse Window Colors
  
 For Text Editing (i.e. Pages, Word)
cmd-BBold
cmd-UUnderline
cmd-IItalic
cmd-TShow Fonts Panel
shift-cmd-CShow Colors Panel
  
 Finder (Including Desktop)
cmd-IGet Info
shift-cmd-NCreate New Folder
  
 Browsers
cmd-RReload Page in Safari or Firefox
F5Reload Page in Firefox
cmd-[ or cmd- ←Back in Browser
cmd-] or cmd- →Forward in Browser
cmd-DAdd bookmark in browser
cmd-TNew Tab in Safari or Firefox

Does anyone else have any favorite mac keyboard shortcuts?