Healthy Meat Alternatives

As I've said before, meat is expensive. As a college student on a limited budget I generally avoid buying meat. So over time I have found recipes and substituted other natural products for the meat that would usually be found in the dish. I don't use tofu often so I won't discuss that here, instead I'll talk about healthy, natural, and somewhat inexpensive alternatives to using meat.

1. Beans. Bean are probably the least expensive on the list. Especially if you buy them dried and in bulk. Although buying them in a can may be easier it is definitely cheaper to buy them dry, and you also avoid the toxins that can come with canned goods. I use at least three different kinds of beans when I make chili, they are chock full of protein and fiber which really adds a heartiness to any meal.
2. Zucchini.  I've used shredded zucchini in lasagna before and found it to be really delicious. You could also use it in spaghetti or in casseroles. I've even seen some recipes where the zucchini is steamed and cut into circular pieces, and then cheese and sauce are put on top to make mini-pizzas.
3. Mushrooms. Mushrooms are a very common substitute. They are used in veggie burgers and in pizza. I personally love mushrooms and throwing them into a lasagna, soup, or tacos. What is particularly advantageous about mushrooms is that they soak up whatever other flavor you're adding to the dish, making them great to bite into!
4. Eggplant.  Like mushrooms, eggplants are thick and dense to bite into, making them a bit more "meaty" than other vegetables. Using eggplant to as a substitute in chicken parmesan is common and quite good, I also used eggplant to make a vegetable casserole topped with bread crumbs that also worked really well. 

Do you use any meat substitutes? What kinds of vegetables or other alternatives do you find work best?