Click for Joy is a great title for anyone just entering the world of clicker training... and it's by a fellow Dog Writers Association of America member.

Clicking With Your Dog is another great read for beginners.  This one is super easy to follow, and guides you through teaching many of the basics.

The original clicker title, Don't Shoot the Dog is a good book for the more advanced reader.  Dealing with the psychology behind the click, it's definitely an operant title that's well worth the price.

The Click-a-Trick flash cards are a super fun and easy way to learn how to train several great tricks.  Teaching your dog to get your keys from your purse is one that's sure to impress.