I've only ever reviewed specific books which related very closely to my area of professional specialty, so I was entirely willing to try out the novelty of reviewing a complete random book (and was therefore hoping it would be a book I hadn't already read). I'm in luck! My randomly assigned book (Lucky Jim, by Kingsley Amis) is not only one I've never heard of, it's about a medieval history professor.
Update: Rumor has it that Penguin is out of books for this initiative. You can still sign up for future releases to review, but they're out of the initial batch.