The Debra Wilson sketches are in many cases wonderful, and extremely funny. Most sketch shows from Oprah's heyday barely even had black women in the role, and the one that did I hesitate to upload, even though I think it's entertaining, because it's mostly just fat jokes (it's the one Kim Wayans did on In Living Color). SNL had Oprah parodies about a dozen times, but this is the only one I would say really works (it's less about her than her banshee audience):
I should also mention the infamous confrontation between James Frey and Oprah. It was queasily compelling, because you knew how much she was seething at not only his lies, but also the damage he had done to her sprawling empire.