Program to Design Diets?

Does anyone know of a good computer program for design and tweaks for diets? I’d like to be able to put in like calories, fats, proteins, carbs I’d like to shoot for in the day and then have a program help me hit those goals? Does this even exsist?

There’s some ipod/iphone apps that let you add up all your macro nutrients and calories by typing in the food you eat daily. My friend has some droid app that lets her take pictures of nutrient labels and it adds up all the stuff that way too.

.Google fitday…You put in the foods you eat and it breaks it down for you and you can set fitness goals.

Fitday.