I'm somewhat ashamed to admit this, even though it *is* kind of healthy, but we often have Luna bars for lunch. DS loves them (yeah, "nutrition for women"
) and they're easy to transport and don't require any refrigeration. We've cut back a bit since DS's palate has gotten a bit more adventurous, as in willing to eat a peanut butter and jelly sandwich.
Other things I pack...crackers (animal, cheddar bunnies, etc), granola bars, clementines, sliced apples, bananas, cheese cubes. If I'm taking a cooler, I'll pack a cold pasta salad or yogurt.