Site stopped working for me for about a week so I said screw it and bought fitday. I like it a lot better. Much more convenient. However I do still actually use nutritiondata when I have trouble finding an odd food.
Its a dataset, not a way of making money n stuff, hence the lack of advertisements.
If you download the entire database, you get a program that you can enter stuff and have it ocme up far quicker.
Nutritiondata use the goverment data for some of their inforamtion, and some other stuff from who-knows-where for other parts, that create a rather odd view of the world. I would trust the USDA dataset over nutrition data anyday