Iman Crosson, Obama Impersonator
Ever since Obama has been out in the public eye in a big way, one man has been posting videos to YouTube of his expert impersonation of the future and now current President. His viewcount alone is enough for us to call him one of the Who's Who on YouTube.
His name is Iman Crosson, and he's got the former Senator from Illnois down pat. You should really check out his work.