Soups take some time to make, but if you make a big pot and freeze part of it in a couple of portions, you can just reheat it...that's a very quick meal, and healthy and inexpensive, too. Couscous and polenta are also really easy and fast to make.
Here's a quick polenta recipe -- this makes about two large servings, but could easily be doubledd:
1 T. Olive oil
Minced garlic, 6 cloves
1/4 t. crushed red pepper
1 1/2 cups finely chopped canned tomatoes with their juice
Vegetable(s) -- I use zucchini, but you could use cauliflower or anything else you like
Saute garlic and pepper flakes in oil for 2 minutes. Add tomatoes and simmer for 5 minutes. Add vegetables and simmer another 5 minutes.
To make the polenta, bring 3 cups water and 1/2 t. salt to boil. Add 1 cup cornmeal (grits) while whisking constinuously. Sir in 1-2 T. butter or margarine. Cover (polenta sputters!) and simmer for 5-10 minutes, stirring often until thickened. Remove from heat and stir in 1/2 cup of grated parmesan (optional). Serve tomato sauce over polenta.
This is a pretty basic recipe -- you could add a can of beans or tofu if you want additional protein, or add/adjust spices to taste.