Over the years, I've read or been recommended a number of books which are essential reading for professional web developers. I've compiled the list of books below to help the community find a comprehensive list of good books that can help them be better coders. 

<h3>JavaScript</h3>

<a href="http://www.amazon.com/gp/product/047022780X?ie=UTF8&tag=rebasbl-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=047022780X">Professional JavaScript for Web Developers</a><img src="http://www.assoc-amazon.com/e/ir?t=rebasbl-20&l=as2&o=1&a=047022780X" width="1" height="1" border="0" alt="" style="border:none !important; margin:0px !important;" /> - My new favorite book. Almost 1,000 pages of VERY detailed JavaScript information. Written by Nicholas Zakas, Yahoo! Principal Front-end Engineer for Yahoo!'s home page and recommended by the YUI team as well. BUY THIS BOOK!

<a href="http://www.amazon.com/gp/product/0596101996?ie=UTF8&tag=rebasbl-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=0596101996">JavaScript: The Definitive Guide</a><img src="http://www.assoc-amazon.com/e/ir?t=rebasbl-20&l=as2&o=1&a=0596101996" width="1" height="1" border="0" alt="" style="border:none !important; margin:0px !important;" /> - Considered the Bible of JavaScript for its thorough coverage of JavaScript. You need to have this in your library, even as a reference.

<a href="http://www.amazon.com/gp/product/1590595335?ie=UTF8&tag=rebasbl-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=1590595335">DOM Scripting: Web Design with JavaScript and the Document Object Model</a><img src="http://www.assoc-amazon.com/e/ir?t=rebasbl-20&l=as2&o=1&a=1590595335" width="1" height="1" border="0" alt="" style="border:none !important; margin:0px !important;" /> - This is a good book to get you familiar with the DOM. 

<a href="http://www.amazon.com/gp/product/1590598563?ie=UTF8&tag=rebasbl-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=1590598563">AdvancED DOM Scripting: Dynamic Web Design Techniques</a><img src="http://www.assoc-amazon.com/e/ir?t=rebasbl-20&l=as2&o=1&a=1590598563" width="1" height="1" border="0" alt="" style="border:none !important; margin:0px !important;" /> 

<a href="http://www.amazon.com/gp/product/1590596803?ie=UTF8&tag=rebasbl-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=1590596803">Beginning JavaScript with DOM Scripting and Ajax: From Novice to Professional</a><img src="http://www.assoc-amazon.com/e/ir?t=rebasbl-20&l=as2&o=1&a=1590596803" width="1" height="1" border="0" alt="" style="border:none !important; margin:0px !important;" /> - The book by Christian Heilmann that really got me past the initial hump of plain 'ole JavaScript. His writing style is awesome.

<a href="http://www.amazon.com/gp/product/1847194141?ie=UTF8&tag=rebasbl-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=1847194141">Object-Oriented JavaScript: Create scalable, reusable high-quality JavaScript applications and libraries</a><img src="http://www.assoc-amazon.com/e/ir?t=rebasbl-20&l=as2&o=1&a=1847194141" width="1" height="1" border="0" alt="" style="border:none !important; margin:0px !important;" /> - JUST BUY THIS BOOK! Stoyan did a great job of outlining OOJS principles and it's been incredibly valuable.

<a href="http://www.amazon.com/gp/product/0596517742?ie=UTF8&tag=rebasbl-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=0596517742">JavaScript: The Good Parts</a><img src="http://www.assoc-amazon.com/e/ir?t=rebasbl-20&l=as2&o=1&a=0596517742" width="1" height="1" border="0" alt="" style="border:none !important; margin:0px !important;" /> - It's certainly a good book and I would recommend reading it after one of the more intro books like JS for Web Developer by Nicholas Zakas.

<a href="http://www.amazon.com/gp/product/1847196705?ie=UTF8&tag=rebasbl-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=1847196705">Learning jQuery 1.3</a><img src="http://www.assoc-amazon.com/e/ir?t=rebasbl-20&l=as2&o=1&a=1847196705" width="1" height="1" border="0" alt="" style="border:none !important; margin:0px !important;" /> - While covering jQuery v1.3, the techniques discussed are still useful and I still recommend the book highly.

<a href="http://www.amazon.com/gp/product/1590597273?ie=UTF8&tag=rebasbl-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=1590597273">Pro JavaScript Techniques</a><img src="http://www.assoc-amazon.com/e/ir?t=rebasbl-20&l=as2&o=1&a=1590597273" width="1" height="1" border="0" alt="" style="border:none !important; margin:0px !important;" /> - John Resig's famous book on advanced JS techniques.

<a href="http://www.amazon.com/gp/product/193398869X?ie=UTF8&tag=rebasbl-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=193398869X">Secrets of the JavaScript Ninja</a><img src="http://www.assoc-amazon.com/e/ir?t=rebasbl-20&l=as2&o=1&a=193398869X" width="1" height="1" border="0" alt="" style="border:none !important; margin:0px !important;" /> - Still not out but considering that John Resig is that author, it's sure to be great.

<a href="http://www.amazon.com/gp/product/0321423305?ie=UTF8&tag=rebasbl-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=0321423305">ppk on JavaScript, 1/e</a><img src="http://www.assoc-amazon.com/e/ir?t=rebasbl-20&l=as2&o=1&a=0321423305" width="1" height="1" border="0" alt="" style="border:none !important; margin:0px !important;" /> - One of the first books I picked up and great overview of the language.

<a href="http://www.amazon.com/gp/product/1590597648?ie=UTF8&tag=rebasbl-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=1590597648">Accelerated DOM Scripting with Ajax, APIs, and Libraries</a><img src="http://www.assoc-amazon.com/e/ir?t=rebasbl-20&l=as2&o=1&a=1590597648" width="1" height="1" border="0" alt="" style="border:none !important; margin:0px !important;" />

<a href="http://www.amazon.com/gp/product/0321491939?ie=UTF8&tag=rebasbl-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=0321491939">Ajax Security</a><img src="http://www.assoc-amazon.com/e/ir?t=rebasbl-20&l=as2&o=1&a=0321491939" width="1" height="1" border="0" alt="" style="border:none !important; margin:0px !important;" /> - Billy Hoffman is the man when it comes to Ajax security and this books shows why.

<a href="http://www.amazon.com/gp/product/0596159773?ie=UTF8&tag=rebasbl-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=0596159773">jQuery Cookbook: Solutions & Examples for jQuery Developers (Animal Guide)</a><img src="http://www.assoc-amazon.com/e/ir?t=rebasbl-20&l=as2&o=1&a=0596159773" width="1" height="1" border="0" alt="" style="border:none !important; margin:0px !important;" /> - Tips & techniques from the jQuery team rolled up in a cookbook style. You can't go wrong.

<a href="http://www.amazon.com/gp/product/1935182323?ie=UTF8&tag=rebasbl-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=1935182323">jQuery in Action, Second Edition</a><img src="http://www.assoc-amazon.com/e/ir?t=rebasbl-20&l=as2&o=1&a=1935182323" width="1" height="1" border="0" alt="" style="border:none !important; margin:0px !important;" /> - This is now updated for jQuery v1.4.x as well as jQuery UI 1.8.x. Definitely a must-have for jQuery developers

<a href="http://jqueryenlightenment.com/">jQuery Enlightenment</a> - Cody Lindley did an amazing job in outlining the best jQuery techniques in this self-published book. Totally worth the price.

<h3>HTML & CSS</h3>

<a href="http://www.amazon.com/gp/product/1430219203?ie=UTF8&tag=rebasbl-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=1430219203">Web Standards Solutions: The Markup and Style Handbook, Special Edition</a><img src="http://www.assoc-amazon.com/e/ir?t=rebasbl-20&l=as2&o=1&a=1430219203" width="1" height="1" border="0" alt="" style="border:none !important; margin:0px !important;" />

<a href="http://www.amazon.com/gp/product/0321509021?ie=UTF8&tag=rebasbl-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=0321509021">Bulletproof Web Design: Improving flexibility and protecting against worst-case scenarios with XHTML and CSS (2nd Edition)</a><img src="http://www.assoc-amazon.com/e/ir?t=rebasbl-20&l=as2&o=1&a=0321509021" width="1" height="1" border="0" alt="" style="border:none !important; margin:0px !important;" />

<a href="http://www.sitepoint.com/books/cssdesign1/?SID=82b54f50488243b44b6b9c7acb10731a">The Art & Science Of CSS</a>

<a href="http://www.sitepoint.com/books/css2/?SID=82b54f50488243b44b6b9c7acb10731a">HTML Utopia: Designing Without Tables Using CSS, 2nd Edition</a>

<a href="http://www.amazon.com/gp/product/1600330045?ie=UTF8&tag=rebasbl-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=1600330045">Head First HTML with CSS & XHTML</a><img src="http://www.assoc-amazon.com/e/ir?t=rebasbl-20&l=as2&o=1&a=1600330045" width="1" height="1" border="0" alt="" style="border:none !important; margin:0px !important;" />

<a href="http://www.amazon.com/gp/product/0321687299?ie=UTF8&tag=rebasbl-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=0321687299">Introducing HTML5 (Voices That Matter)</a><img src="http://www.assoc-amazon.com/e/ir?t=rebasbl-20&l=as2&o=1&a=0321687299" width="1" height="1" border="0" alt="" style="border:none !important; margin:0px !important;" />

<a href="http://books.alistapart.com/product/html5-for-web-designers">HTML5 For Web Designers</a>

<a href="http://www.amazon.com/gp/product/059615593X?ie=UTF8&tag=rebasbl-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=059615593X">CSS Cookbook, 3rd Edition (Animal Guide)</a><img src="http://www.assoc-amazon.com/e/ir?t=rebasbl-20&l=as2&o=1&a=059615593X" width="1" height="1" border="0" alt="" style="border:none !important; margin:0px !important;" />

<a href="http://www.amazon.com/gp/product/0596802447?ie=UTF8&tag=rebasbl-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=0596802447">CSS: The Missing Manual</a><img src="http://www.assoc-amazon.com/e/ir?t=rebasbl-20&l=as2&o=1&a=0596802447" width="1" height="1" border="0" alt="" style="border:none !important; margin:0px !important;" />

<h3>Site Performance</h3>

<a href="http://www.amazon.com/gp/product/0596529309?ie=UTF8&tag=rebasbl-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=0596529309">High Performance Web Sites: Essential Knowledge for Front-End Engineers</a><img src="http://www.assoc-amazon.com/e/ir?t=rebasbl-20&l=as2&o=1&a=0596529309" width="1" height="1" border="0" alt="" style="border:none !important; margin:0px !important;" />

<a href="http://www.amazon.com/gp/product/0596522304?ie=UTF8&tag=rebasbl-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=0596522304">Even Faster Web Sites: Performance Best Practices for Web Developers</a><img src="http://www.assoc-amazon.com/e/ir?t=rebasbl-20&l=as2&o=1&a=0596522304" width="1" height="1" border="0" alt="" style="border:none !important; margin:0px !important;" />

<a href="http://www.amazon.com/gp/product/059680279X?ie=UTF8&tag=rebasbl-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=059680279X">High Performance JavaScript (Build Faster Web Application Interfaces)</a><img src="http://www.assoc-amazon.com/e/ir?t=rebasbl-20&l=as2&o=1&a=059680279X" width="1" height="1" border="0" alt="" style="border:none !important; margin:0px !important;" />

This is certainly not all inclusive and I'm sure there are other books out there that have been great. If you feel very passionate about a specific title, let me know via the comments and I'll check it out.