What are some good "cook and freeze" or "prepare ahead" meals?

You can freeze most lasagnes or casseroles. Roast a few chickens and cook a roast beef, and you can use them in sandwiches, salads, stirfry, quiche or frittatas. Cook a big batch of spaghetti sauce and freeze into several meal-sized portions. It's always better the second day anyway! You can put it over spaghetti, or get some frozen cheese-stuffed shells and bake it with the sauce over while you toss a salad, or mix with pasta and mozzarella and top with parmesan cheese for baked ziti. Make a big batch of chili verde; the rice and beans take no time while it reheats. Why heat things up? Make a big batch of potato salad and pasta salad and marinated cucumber salad for cold roasted chicken dinners. Make a batch of ceviche. It "cooks" itself overnight in the fridge. Make gazpacho.