If you are a web developer the following resources would be really useful to u.

Debuggers

• Firebug debugger for Firefox
• Microsoft Script debugger for Internet Explorer
• Internet Explorer Developer Toolbar
• IE Leak Detector (Drip/IE Sieve)

Reference

• The Javascript Reference Series - Essential Javascript (Numbers, Strings, Arrays, Dates)
• VisiBone Javascript Quickreference
• Quirksmode Compatibility Tables (Core, HTML, CSS, Event Handling)
• JScript Language Reference (Internet Explorer) (HTML and DHTML Reference)
• JavaScript Language Resources (mozilla) (Core JavaScript 1.5 Guide, Core JavaScript 1.5 Reference, Gecko DOM Reference)
• Web Specifications Supported in Opera 9
• W3C DOM (HTML) Level 1 specification

Articles - Beginners

• General introduction (Object detection)
• Several indispensable articles by Douglas Crockford (The Wrrrld's Most Misunderstood Programming Language, A Survey of the JavaScript Programming Language)
• Behavioral Separation
• Seven JavaScript Techniques You Should Be Using Today
• Optimizing JavaScript for Execution Speed
• Memory Leakage in Internet Explorer

Articles - Advanced

• Scope in JavaScript
• JavaScript Closures for Dummies
• Higher Order Programming
• Higher-Order JavaScript
• The Little JavaScripter

Code collections

• JSAN
• DZone Snippets > javascript
• WebFX

Frameworks

• Mochikit (Animator)
• Prototype (script.aculo.us)
• jQuery (jQuery UI)
• YUI (Ext)
• Dojo toolkit
• Mootools
• X library
• Core javascript library

XMLHttpRequest / AJAX

• Ajax: A New Approach to Web Applications
• List of Ajax Mistakes
• AjaxPatterns.org
• Guide to Using AJAX and XMLHttpRequest
• AJAX:Getting Started

Integration with Flash

• SWFObject
• Soundmanager2
• Dojo.Storage

Blogs

• Ajaxian
• Yahoo! User Interface Blog
• Sitepoint Blogs > JavaScript & CSS
• dean.edwards.name
• Erik's weblog & Emil’s Chronicle

Thanks to Sitepoint for providing this valuable information.

If you find anyother resources that are useful do comment here!

Naveen