Quickly confirming or rejecting Faces in iPhoto
When confirming wether faces recognized by iPhoto '11 are actually correct, some will be wrong and need to be rejected.
iPhoto gives the hint to 'Click to confirm or Option-click to reject,' yet the easier and faster way to reject would be to simply double click the image, after which it will be marked as 'Not (name).' [crarko adds: I tested this, and it works as described. Yet another undocumented feature of iPhoto.]
Source: http://feeds.macosxhints.com/click.phdo?i=4d3b95452cf440aa47c9e5eb7f34407a