I just downloaded a free app from iTunes called Lose it! Click here to see
It basically lets you enter your current weight, the weight you would like to be, your height and age. It then tells you how many calories you can have each day and uses a little chart to see how many are left. It allows you to enter the food you have eaten and how much. It figures out how many calories that was.
It seems to have a lot of foods listed. I am going to give it a go and see how it works. I like that I can take it with me.