He has a weekly trivia contest that you can sign up for. The questions are hard, but interesting and often quirky. From the answers to one of last week's questions:
5. Who dated Iola Morton and Callie Shaw? The Hardy Boys. Did you know Iola was killed by terrorists in 1987? No kidding. Car bomb. I think that officially ended my childhood.Check out http://www.ken-jennings.com/. His blog is good. To get on the trivia mailing list, go there, select "About Ken", and scroll down to see the box on the left side.