Paula Wolfert's World of Food and The Cooking of the Eastern Mediterranean are the two I use. Lovely, flavorful, mostly healthy food in both of them.
I've had Couscous and Other Good Food from Morocco on my wish list for a long time but have never gotten around to purchasing it. It's probably her most well-known book. That and The Cooking of Southwest France--which will harden your arteries just by reading it. I admit, I've never actually cooked anything from the latter book. It's heavier food than I usually like to eat but it makes for fascinating reading.
She's also got a book on clay pot cookery I've looked at but have stayed away from because the last thing I need is to accumulate more cookware--especially space-hogs like special-purpose clay vessels. The recipes sound wonderful, though. Very slow food.