http://www.newschoolphoto.com/blogme/2007/...esome-shortcut/
From NewSchool's Rebel Fish:
Rebel Fish gasped outloud when she stumbled on this one.
Go to library mode.
View thumbnails OR zoomed into a single image.
Hold command down (the apple key)
You can then just put your fingers on the arrow keys and….
Left / Right arrow go forward back (no big surprise there)
Up arrow will raise your flag status (e.g., if no flag, it is now a pick)
Down arrow will lower your flag status (e.g., if no flag, it is now rejected)
So. You simply cruise through your library thinking UP for “I like it!” and DOWN for “You suck!”
Tada!
