There are lots of them.some are more user friendly than others.It does make counting or having a close idea on what your taking in easier.
•CalorieKing
Lots of information on commercial products
•Calorieking.au (aussie version of above) for Bigchef and the other Aussies.
As above, only for the land downunder
•Nutridiary
Good basic and accurate tool that allows you to create favourite meals for ease of logging. Tracks exercise and water intake too
•DailyBurn
Easy to use, Accurate, Good range of foods, Very funky additional applications such as bar-code scanning
•CalorieCount
This has a cool recipe tool where you simply type in a list of foods and how many servings you want and it calculates it out. < VERY handy!
•Fitday
Inaccurate in regards to calories from carbs/ fibre and can give false information on servings sizes... Ok if you log all your own foods