I originally signed up for myfitnesspal for the weight loss tracker... not for the site. My mom and sister-in-law both encouraged me to use it sometime last year. I listened, not. Well... now, I finally completed my profile and opened it up. I should have done this months ago!
You can track Protein, Vitamins, Calories, Fat, Sugars, Salts, and several other characteristics of your diet.
My wife was worried that I might not be getting enough calories... well, upon first entering my info I came up with 2,000 calories for today. Then I changed the apples from Large to Medium and 1,806 came up as my caloric intake for the day.