This lovely screencast series was produced by Jeffery Way from http://blog.themeforest.com - respect for a great series for begginers
jQuery For Absolute Beginners Part 1
jQuery For Absolute Beginners Part 2
jQuery For Absolute Beginners Part 3
jQuery For Absolute Beginners Part 4
jQuery For Absolute Beginners Part 5
jQuery For Absolute Beginners Part 6
jQuery For Absolute Beginners Part 7
jQuery For Absolute Beginners Part 8
jQuery For Absolute Beginners Part 9
jQuery For Absolute Beginners Part 10
jQuery For Absolute Beginners Part 11
jQuery For Absolute Beginners Part 12
jQuery For Absolute Beginners Part 13
jQuery For Absolute Beginners Part 14
jQuery For Absolute Beginners Part 15A
jQuery For Absolute Beginners Part 15B
Advanced Topics
This section contains further jQuery tuts by Jeff Way, beyond the Absolute Beginners series
An Overview of jQuery's AJAX Capabilities
How to create a simple jQuery plugin
How to make Ajax requests with pure JavaScript
Know your past. This screencasts shows you how complicated it used to be to make a simple Ajax request with pure JavaScript. It's a good reference for jQuery programmers, who can do the same with just one line of code