Here are a few books I really want to see:
A serious treatment on the rise of cable television, filled with behind-the-scenes interviews with both the suits and artists who made it happen. Journalism credentials necessary.
American history in the 19th century. The issue chosen needs to be specific, but with enough umph to carry a whole book. I also think that there's room for more history books focusing on a single year or even a few months (April 1865 is a great example).
A gritty, hard-boiled urban fantasy mystery series. Imagine Lehane or Connelly, but paranormal. Must be set on earth in the present or very near future.