Mac OS X keyboard shortcuts

 KEYBOARD SHORTCUT   
DESCRIPTION
MENU COMMANDS
Shift+Apple+Q 
Log out
Shift+Option Apple+Q
Log out immediately
Shift+Apple+Delete  
Empty Trash
Apple+H   
Hide Active Application (Doesn't Work With Adobe Applications)
Option+Apple+H   
Hide All But The Active Application
Control+Eject   
Shut Down, Sleep, or Restart Options
Apple+Control+Eject   
Quit all applications and Restart
Apple+ . (period)   
Stop a process
Apple+ , (comma)   
Open Preferences for Active Application
Option+Apple+D   
Show/Hide Dock
Control+Up Arrow   
Move up one page
Control+Down Arrow  
Move down one page
Option+Apple+Esc   
Force Quit
FILE MANAGEMENT
Command+N   
New Finder window (or New Blank Page in Some Applications)
Shift+Apple+N   
New Folder (Must Be In Finder Window For It to Work)
Apple+O   
Open Another Existing Document
Apple+S   
Save
Shift+Apple+S   
Save as
Apple+P  
Print
Apple+W   
Close Window
Apple+Command+W
Close all Windows
Apple+I   
Get Info
Option+Apple+I   
Show Attributes Inspector (Limited use – varies by application.)
Apple+D  
Duplicate
Apple+Q   
Close Application
Apple+L   
Make Alias
Apple+R   
Show Original
Apple+T   
Add to Favorites
Apple+Delete   
Move Highlighted Items to Trash
Apple+E   
Eject
Apple+F   
Find
EDITING
Apple+Z   
Undo
Apple+X   
Cut
Apple+C   
Copy
Apple+V   
Paste
Apple+A   
Select All
Apple+ {   
Align Left - Only Works in Some Applications
Apple+ }   
Align Right - Only Works in Some Applications
Apple+ | (pipe)   
Align Center - Only Works in Some Applications
Apple+ ; (semicolon)   
Check Spelling - Only Works in Some Applications
Shift+Apple+C  
 Show Colors palette in application - Only Works in Some Applications
Apple+T   
Show Font palette in application - Only Works in Some Applications
VIEW MENU
Apple+1  
View as Icons
Apple+2   
View as List
Apple+3   
View as Columns
Option+Apple+T  
Hide Toolbar
Apple+J   
Show View Options
MOVING AROUND
Apple+ [   
Back -  Must be in Finder Window
Apple+ ]  
Forward -  Must be in Finder Window
Shift+Apple+A   
Applications -  Must be in Finder Window
Shift+Apple+F  
Favorites -  Must be in Finder Window
Shift+Apple+G   
Goto Folder -  Must be in Finder Window
Apple+K   
Connect to Server -  Must be in Finder Window
CONTROLLING WINDOWS
Apple+M   
Minimize Window
Option+Apple+M   
Minimize All Windows
GETTING HELP
Apple+ ?   
Open Mac Help
UNIVERSAL ACCESS
Option+Apple+* (asterisk)   
Turn on Zoom
Option+Apple+ = (equal)   
Zoom in
Option+Apple+ - (minus)   
Zoom out
Control+Option+Apple+* (asterisk)  
Switch to White on Black
COMBINE KEYBOARD WITH MOUSE
Option+Drag   
Copy to new location
Option+Apple+Drag   
Make alias in new location
Apple+Drag   
Move to new location without copying
SCREEN SHOTS
 will leave a .pdf file on desktop to convert to a graphic
Apple+Shift+3
Take a picture of the screen
Apple+Shift+4   
Take a picture of the selection
Apple+Shift+4, then press Control while selecting
Take a picture of the screen, place in clipboard
Apple+Shift+4, then Spacebar
Take a picture of the selected window

List taken from http://www.themacobserver.com/columns/firstmac/2005/20050422.shtml