Right now I'm reading Inheritance by Christopher Paolini. It's the fourth book in the series that started with Eragon. Something that made me very happy was that in the this book and the previous one (Brisingr) there was a reference to Dr. Who. In Brisingr two of the characters are sitting by a campfire, and one of them writes: "Adrift upon the sea of time, the lonely god wanders from shore to distant shore, upholding the laws of the stars above." It has nothing to do with the plot of the book; it's just an idle mention. I actually had to go back and reread it because I didn't catch the Doctor reference at first. I realized it was referencing him when I read the author's note at the end of the book. It reads, in part: "For those who caught the lonely god reference when Eragon and Arya are sitting around the camp fire, what can I say? I'm a fan. The Doctor can travel any where, even alternate realities." In Inheritance the reference is even more minor. One character is listing all the fantastic things he's seen in the world, and in his list he includes, "rooms that are bigger on the inside then on the outside".