The woman who writes A Year of Slow Cooking has at least one family member who eats gluten-free. Here's a listing of her vegetarian recipes:
http://crockpot365.blogspot.com/2005/12/vegetarian.html
And tell your darling husband that the next time he complains, he gets to plan, shop and cook for the next month.
I'm curious as to how old your vegetarian son is. If he's old enough to be the only vegetarian in the house (i.e., it is his choice, not a family thing) isn't he old enough to cook his own dinner? Maybe make a pot of a vegetarian protein on the weekend that can be served along with the other dishes during the week?
I think I'd also be tempted to make lunch the bigger meal and make dinner a lighter meal. A salad base with different toppings for different people (beans or animal protein).
Not sure if it is gluten free, but the Morningstar Farms veggie crumble (fake ground beef) is pretty good in stroganoff, chili, sloppy joes, etc. That might make everyone happy. I imagine it would also be good in a lasagna or baked ziti made with GF noodles.
Have you tried making frittatas? Or crust-free quiche?