Where’re my books?

I loan out books to everyone. With a few exceptions, I don’t expect to get them back.
But over the last couple of months, every time I’ve gone to look for a specific one to loan, it’s already gone. Tod asked last night “Do you know what happened to His Dark Materials?” Someone is enjoying it, I imagine, but I have no idea who it might be.
So now I’d like to figure out who has what, so I can engineer trades to get the books into different hands. It’s like solving word problems. “If Friend A in Meguro wants to read book X which is currently held by Friend B in Kanagawa, how long will it take to get book X to Friend A?”
Do you have any books I loaned you? Which ones? Leave me a comment or drop me a mail…