Well, I'd think you'd only need such a cook book if you're trying to make foods that use gluten replacers/substitutes, because those sometimes require specialized technique and knowledge. Otherwise your existing knowledge should be up to the task, n'est ce pas?
I know it's tempting to go the Asian route, because they have many big non wheat cultures, but you have to be careful because a lot of the seasoning products have wheat in them. Soy sauce especially. I know kikoman makes a gluten free soy sauce you can order. Also note that tamari doesn't always mean wheat free.
Some ideas for gluten free apps
Falafal (ground soaked (but not cooked!!) chickpeas and/or dry peeled fava, season with pureed onion, cumin, salt/pepper, mince parsley and garlic. Fry like fritters. Sauce is a little tahini thinned with lemon and flavored with garlic)
Msebbha (soft cooked chickpeas dressed with tahini, garlic, salt, olive oil, lemon juice. Sprinkle mince parsley and paprika on top) Could serve it in a lettuce or other vegetable cup.
Hummus or baba ganoush is really popular around here with vegge sticks.
Sold a lot of roasted/grilled vegetable applications. Usually platters
Sold two variations of stuffed pilqillo peppers when I worked in Spanish restaurants. One stuffed with oil pack tuna, the other with chopped artichoke hearts.
Pieces of Spanish Tortilla were popular and OMG cheap.
Tofu pok stuffed with shrimp, then fried is always popular.
You can make a nice dumpling dough with rice flour and tapioca starch, but it is a little tricky to work with.
Atomic Buffalo Turds and Moink Balls have been very popular every time I've served them. Haven't really seen them outside of niche BBQ joints though.
Entrees shouldn't be a problem unless you are wedded to a roux based sauce or need to en croute something.
Desserts: I would stick with a seasonal fruit fool or mousse. Dunno if it would be worth the work to reformulate a charlotte to use gluten free. Maybe a custard or something. There is always the flourless molten chocolate cake, but that is a bit cliche.