Lean ground beef can go a long way. Spaghetti, for instance. Spaghetti sauce has virtually no fat, while noodles tend to have around 7 grams of protein and merely 1 gram of fat per serving. Chili, plain ol' burgers if you prepare them correctly, etc.
Also, you can buy Asian vegetable stirfry at the supermarket, then toss in some chicken with it.