I don't ever watch Jimmy Fallon's show, but I think the guy is totally hilarious and a genius at impersonations. I heard him on NPR one day talking about how we got selected for SNL and I was laughing out loud in my car.
Justin Timberlake was on his show this week and they did a follow up to their "History of Rap" medley from last year. I think this year's is even better. Here's "History of Rap, Part 2"