Cock-eyed optimist that I am, I'm excited to see several new books on The Man coming out soon:
Richard III: The Young King by Josephine Wilkinson. This is part one of a two-part biography of Richard, and it's winging its way to me now. (Wilkinson also has a biography of Mary Boleyn in the offing.)
Richard III by Ann Kettle. This is published by Routledge and is offered at the whopping price of 54 pounds, so I assume it's meant for the academic market. Every time I try to search for it on Routledge's site, it times out on me; maybe you'll have better luck.
Richard III and the Death of Chivalry by David Hipshon. According to its description, this book attributes Stanley's betrayal of Richard to Richard's support of the Harringtons in the Harrington-Stanley feud.
On the fiction front, I posted a review of Emma Darwin's A Secret Alchemy on my main blog. I really enjoyed it. It features two historical characters, Anthony and Elizabeth Woodville, and one fictional contemporary character, a historian who's writing an academic study of the brother and sister. Richard III makes only a couple of appearances, but much of the story takes place during his reign.