FoodBrowser is a Mac OS X application that lets you drag and drop foods from a nutrition data table onto a daily intake table. This allows you to keep a History of the Calories derived from the foods you eat.
All the data in the nutrition table is computed per 100 grams of product. After dropping data in the calorie calculator table, you can double-click the "Qty" column and change the quantity to the actual quantity consumed. FoodBrowser will recompute the total as soon as any change in the quantity column is entered.