I go to McDonalds somewhat often, and typically I order a spicy chicken sandwich off of the dollar menu with instructions to go light on the mayo (otherwise they glob it on there) and add mustard and a slice of tomato and a small fry with no salt. (The main purpose of asking for no salt is so they make it fresh rather than from the pile that's been sitting there. The sodium content otherwise doesn't bother me.) I also get a courtesy water cup.
Total is somewhere like $2.50 and typically leaves me satisfied. The spicy chicken in particular helps with that (I've always found that spicy foods help me feel sated.) I think in all its 400 calories, which is slightly higher than the chicken salads I get from subway even more often.
I guess I'm just one of those weirdos who doesn't go calorie crazy at fast food joints, nor do I eat sugary breakfasts (usually a 250 calorie Jimmy Dean turkey sausage, cheese, and egg biscuit.) But in my defense, I work in an office type environment with little physical activity (until I get home and then do a 6 mile daily bike ride, and then dinner always has less than 1,200 calories.)
And yes, this is all a part of my ongoing weight loss plan (which is succeeding rather well and has been ongoing for a year. Whoever says you can't diet and eat fast food is dead wrong.)