An almost nutritionally-perfect snack is almond butter on rice cakes. Low calorie, good fats and decent protein.
I bought some natural almond butter and it isn't bad. The oils separate, like natural peanut butter, and you have to work a bit more to spread it out, but it tastes pretty good.
I've got the almond butter in the office fridge and the rice cakes in my drawer, so I'm hoping I can use them for afternoon snacks and prevent that end of day hunger.