If you are looking for nutritional information on branded products, you can go to:

If you are looking for product information on items that are not branded, you can go directly to the manufacturer's website.

Also, you can go directly to this site:
This is the USDA National Nutrient Database for Standard Reference.

You can look up thousands of foods on this site and even download a tool onto their computer that will calculate the nutritional value based on what serving size they enter.  This should be helpful to any schools, health care, daycare, or anyone else trying to manage their menu.