I scoured the first four pages of Google search results for "interview questions", and found only 3 examples related to this question. In two and a half decades of my technology career, I'm sure that I've been interviewed by several hundreds of people, and only once was asked this simple question.
What do you read?
For a starting point, it is always helpful to have a generic question or two that can break the ice and get a candidate talking and a bit comfortable before getting the candidate into more challenging material, but frankly the score from yesterday's baseball game doesn't really give you any relevant insight. If you give a candidate enough time to answer this question, you could learn a lot.
Apparently being such a rare question, the candidate will surely not be expecting it. Yet answering this question can't be faked, so you can get a very quick perspective on the candidate's honest reaction.
The few related interview questions that are posted on the Internet are typically very specific: what is the last book you read? But if you leave the question open-ended (what do you read?), the candidate could reasonably discuss books, magazines, newspapers, journals, blogs, marketing reports, cookbooks, even the book they read to their toddler last night - it's all fair game! And it's also up to the candidate to figure out that they are being invited to reveal a bit of information about themselves, and do not need an answer having a close relationship to the open position.
Does the candidate keep current with their profession? Do they improve their skills? Do they have broad interests? Are they a good cultural fit? Almost no matter what professional position is being considered, practically any knowledge worker in today's economy is required to read, and often to read a lot. If the candidate can't process information more detailed than powerpoint, you may want to think twice before hiring.
My own reading? http://www.goodreads.com/review/list/6961335 You'll find a lot of material about shipwrecks. I can't explain that.