HowStuffWorks.Com - This site offers great information on chocolate and how it is produced.

The Exploratorium - A wonderful site filled with information, pictures and even a video tour of a chocolate factory.

Field Museum - This site originates from the Field Museum in Chicago and offers an abundance of information, pictures of their Chocolate Exhibit, and even lesson plans.

Chocolate: Savor the Flavor by Elaine Landau.
A nonfiction book about chocolate.

Chocolate (What's for Lunch) by Claire Llewellyn.
One of a series of books about different types of foods.

A Chocolate Moose for Dinner by Fred Gwynne.
This book is great for a lesson homonyms and word plays.  A little girl shows what she interprets different phrases to mean.  For example, she envisions a large size chocolate moose coming to dinner, rather than a bowl of chocolate mousse! 

Chocolate: Riches from the Rainforest by Robert Burleigh.
This book is filled with good information, history, and pictures about chocolate and its production.

Chocolatina by Erik Kraft.
This is what happens when a little girl learns the lesson, "you are what you eat"!

Cocoa Ice by Diana Karter Appelbaum.
This is the story of two different parts of the world and how they come together to make a tasty dessert.

Curious George Goes to a Chocolate Factory by H.A. and Margret Rey.
This little monkey causes some havoc and the chocolate factory!

The Hershey's Milk Chocolate Bar Fractions Book by Jerry Pollotta.
A great book to use for teaching fractions in a math lesson.

I Like Chocolate by Robin Pickering.
A simple, nonfiction, easy reader.

The M&M's Brand Chocolate Candies Counting Board Book by Barbara Barbieri McGrath.
A very simple counting book, best used with young children.

More M&M's Brand Chocolate Candies Math by Barbara Barbieri McGrath.
More complex math activities using m&m's.