Nicole Rivelli / NBC
Oprah Winfrey on '30 Rock'
Sure, we understand that the critically acclaimed yet ratings-challenged "30 Rock" has to do what it can to wrangle viewers, but many of the A-list cameos the show has employed for that purpose have been seriously subpar. Jerry Seinfeld's and Jennifer Aniston's appearances on the series were equally lukewarm. Oddly enough, the standout cameo of 2008 came courtesy of non-comedian Oprah Winfrey, who played herself, opposite an advice-hungry Liz Lemon during a plane flight. Was it a gimmick? Yeah. Did it work? Totally.