A caricature should resemble the subject and be funny at the same time. The works of German artist Patrick Strogulski have it all.
Other great caricatures:
Amazing Caricatures of Celebrities (50 pics)
Caricatures That Are Pure Awesomeness (22 pics)
Impressive Caricatures (58 pics)
Drawings and Caricatures of the Famous (76 pics)