Actually I've revised my opinion of the Compleat Ankh-Morpork a lot. I already loved it (and the map in particular is everything my geeky little heart could ever have dreamed of) but as my first post indicates I had some niggles.
I didn't much look at it for months, but getting it off the shelf again I find I've done the book a disservice in my memory. The illustrations are charming and the crowds a lot more diverse than I gave them credit for. Originally I found the directory part a little dull because it hadn't quite clicked in my brain that these aren't whimsical names made up specially for this book, these are all businesses mentioned at some point in the novels themselves. That's pretty cool.
Now I think they ought to publish an accompanying guide to the Guilds and institutions of A-M. There's a brief summary of each Guild in the Compleat A-M, but with 40 books in the series, each Guild has its own eventful history. It would be nice to have them recorded int heir own book. I found myself trying to use the Compleat A-M to check a fact the other day (who preceded Downey as Chief Assassin? Yes, I know, Cruces, I found the info online) and it doesn't go into that detail. Which is fair enough. But I think that means there's room for an accompanying guide...