I get asked a lot about where to find resources for learning AppleScript, so far these are the best ones I know of. If you would like others added to the list please post them in comments. :)

Training Scripting Matters, Inc.
AppleScript Pro Sessions

AppleScript Pro Sessions is run by two of the best AppleScripters in the world, Ray Robertson and Shane Stanley. I attended an ASPro a couple of years ago and the training I received changed my life. I understood so much about scripting that I automated 90% of my daily workflow within a few months of attending the seminar. One of the major benefits of attending this training is the private mailing list you get to join. This is an invaluable resource for an AppleScripter.

I can't recommend this training enough! It's a life changer!

AppleScript Resources Videos and Podcasts Mac Automation Made Simple with Ben Waldie iTunes Podcast
Excellent series of video podcasts.

VTC.com Ben Waldie Video Training Series
Ben covers all the basics of AppleScript in this seven hour course.

AppleScript Resources Websites MacScripter.net
The number one place to get help from friendly, experienced AppleScripters!
If you are going to script, joining this forum is a must.

MacScripter has an unScripted section with many wonderful tutorials.

Mac OS X Automation
Not only does this site cover AppleScript but it also covers Automator and the new Services capability of Snow Leopard. This site is run by Sal Soghoian who heads up Apple's Automator and AppleScript departments. This is a very informative site and one you should bookmark!
AppleScript: The Language of Automation
Beginner’s Tutorial: The First Step
Essential Sub-routines: Overview
AppleScript Language Guide AppleScript Resources Books Learn AppleScript: The Comprehensive Guide to Scripting and Automation on Mac OS X by Hamish Sanderson
This book is up to date for Snow Leopard! A must have for Snow Leopard users.

AppleScript - The Comprehensive Guide to Scripting and Automation on Mac OS X Second Edition by Hanaan Rosenthal
If you are new to AppleScript then this is the book for you. You will get a good grounding in the basics and once you have done so pick up a copy of Matt Neuburg's book below.

AppleScript - The Definitive Guide by Matt Neuburg
If you are already a programmer and want to learn the ins-and-outs of AppleScript then Matt will not dissapoint you. He covers all the intricate details of AppleScript. You will like this book!