L&W cover the Japanese. Whitley has done a good job with the Germans. Red Admiral mentioned the Italian book (which is one of a series of books including titles on battleships, destroyers, torpedo boats, etc). The real gap is with the Allied cruisers. Steve McLaughlin is considering a Russian book, but I'm not sure where he stands on that; in the World War II setting, frankly, there's not much to cover. (Vladimir and I go in-depth with the Kirov-class light cruisers in Warship 2009.) The French cruisers are well covered in French books, but if you want any details, you have to track down individual volumes of Warship and Warship International, and some ships like Emile Bertin continue to be off the radar. The British have a book by R&R, but if you want armor schematics, you're out of luck; if "Smurf" is going to take care of this, that's great. The American cruisers are covered in Friedman, but again, no armor schematics; this is one of the things I whine about in my cruiser booklet. Many people think American cruisers were the most heavily armored, and that's not quite the case. In my opinion, of all the wartime light cruisers and heavy cruisers, the best-armored is Italy's Zara class. Wonderful ships.
I have no plans to tackle this subject, but if I can help with the British book, I will. If I take on a cruiser subject, I think it's more likely that I'll focus on armored cruisers, which have been almost totally ignored in the publishing world. That wouldn't be for a while, though; I've got plenty on my plate at the moment.