Eat This Much is a clever webapp that helps you plan your diet based on how many calories you want to consume over the course of a day. You tell it your calorie maximum, how many meals you want to eat and it provides you with a meal plan for the day.
If this sounds familiar, that's because Eat This Much is essentially version 2.0 of previously mentioned Swole.me. It offers a number of algorithmic improvements (so you won't get the occasional strange meal like a pound of bacon for breakfast), allows you to add dishes you like if you want, and provides a grocery list for when you need to go pick up the items at the store. You can restrict certain foods if you want, too, if you have any allergies or other dietary needs.
It's a great way to quickly plan your meals for the day when you don't have time to figure out healthy, balanced options. In fact, if you hate food shopping, it's a good way to help you cut down your time in the store, too.