In-depth Tutorials:

.appendTo()

Video tutorials for both JavaScript and jQuery with progress tracking.  These cover the functions such as the math and string functions quite well.
http://learn.appendto.com/lessons

30 Days to Learn jQuery

A video series by notable Nettuts+ author Jeffrey Way. This is a very extensive set of tutorials which covers the basics to advanced uses of the jQuery framework.
http://tutsplus.com/course/30-days-to-learn-jquery/

Code Academy

A more interactive way of learning JavaScript through actually using it to progress through the language.  This is a console environment based interactive site.
http://codecademy.com

Tools:

FireBug

A valuable plugin for FireFox which allows one to inspect the DOM, debug scripts and output to the console (and much, much more).
http://getfirebug.com/

JS Fiddle

An in browser testing environment which lets one build, test and share pages with HTML, CSS and JavaScript.
http://jsfiddle.net/

JS Bin

Another in browser testing environment which lets one build, test and share pages with HTML, CSS and JavaScript.
http://jsbin.com

JS Lint

A JavaScript validator.
http://jslint.com

JavaScript Regex Generator

An in-browser regular expression generator for JavaScript.
http://jslab.dk/tools.regex.php

JS Min

Minifies source code to optimize and reduce filesize for page loads.
http://fmarcia.info/jsmin/test.html

GitHub

Source Version Control and Social Sharing
http://github.com/

Reference Material:

jQuery Documentation

http://docs.jquery.com/Main_Page

jQuery Source

http://github.com/jquery/jquery

Mozilla  JavaScript Reference

http://developer.mozilla.org/en-US/docs/JavaScript/Reference

Content Delivery Networks:

Google

http://developers.google.com/speed/libraries/devguide#jquery

jQuery

http://code.jquery.com/

Microsoft

http://asp.net/ajaxlibrary/cdn.ashx#jQuery_Releases_on_the_CDN_0