Jimmy Fallon, in Los Angeles this week preparing to host the Emmys this coming Sunday, showed up last night on the set of America's Got Talent to show off some of his talent impersonating various other comedians. As in: Jerry Seinfeld, Bill Cosby, Chris Rock, Robin Williams, Norm MacDonald, Gilbert Gottfried, Pee-wee Herman, Jeff Foxworthy, Eddie Murphy, Larry the Cable Guy, Steven Wright and Adam Sandler. For background, you can watch Jimmy Fallon's longer impersonation medley from Bonnaroo 2009!

Roll it!