This extensive food database offers at-your-fingertips information on carbs, calories, fat, protein, fiber and other elements of common foods, and does so in realistic and customizable portions. Includes generic foods, name brands and fast food options.

Also provides thorough explanations of food building blocks (what is protein, what does it do, how much do you need?). Like many commercial sites, it sells scales, blood pressure monitors and diet plans, but the pitch is unobtrusive and all the good information is free. Affiliated with Boston-based Joslin Diabetes Center, the world's largest diabetes research center.

http://www.calorieking.com/

— American Diabetes Association

Though aimed at diabetics, the site contains great nutritional information for anyone who cooks. Offers tips for cramming more healthy foods into your lifestyle. Best feature is My Food Advisor, which offers food suggestions based on the amount of carbs, calories or fiber you're after, and lets you calculate the nutritional value of meals you prepare.

http://www.diabetes.org/home.jsp

— MyPyramid.gov

The federal government's resource for general information on healthy eating and living. The best feature is a menu planner that creates a bar graph of your nutritional needs, based on body type and exercise habits. Also includes a fun space-themed game to teach children about making healthy choices.

http://www.mypyramid.gov/

— American Dietetic Association

Excellent source of general nutrition information. The site is somewhat heavy on fact sheets and tips from food manufacturers, but the information is good, the authors are clearly stated and each entry is vetted by ADA's review board.

http://www.eatright.org/cps/rde/xchg/ada/hs.xsl/index.html

— Nutrition Data

Owned by CondeNet, the Web arm of Conde Nast Publications, this site is jammed with helpful calculators, including one that will do a nutritional analysis of your recipes. It even has search tools that help you find ingredients high or low in specific nutrients, such as low sugar or high fat.

http://www.nutritiondata.com/