Aebersold's site lists "Mini Real Books" in C a Bb. Here's a link. It says they're 5.5" x 8.5."

On a related note I have a small book called "Pocket Changes," but it only has the changes.

And as a random aside, these legal real books make me feel a little old. "Back in my day you had to keep your voice down when inquiring about a Real Book. And my Pocket Changes only had the first letter and a blank line for each tune. You just happened to get a sheet of paper listing a bunch of standards a week or so later which coincidentally allowed you to fill in the blanks."