Several sites are beginning to get more and more visits for its very deep library of articles, information and resources on web design today.
One of them is Smashing Magazine. Another site has popped-up on my always visit list, and which I subscribed to is Mashable. Excerpted (and edited) below is from an article in Mashable – Web Design Toolbox: 130+ New Tools to Make You a Better and Faster Designer.
Edited because I went through all of the 130+ sites listed (yes it was tiring) and in this article, have kept only the ones that matters or should matter to breed of web designers who on a daily basis strive to achieve the balance of creative design and front end engineering.
2 strong criterias behind what gets removed and what don’t from the original list is that first, the sites must be free and no registration required. And second, that it must be an engine that is useful to the creative designer as the end user. Most importantly in the end, even if these sites don’t make you a better designer, they most definitely will make you a faster web builder.
[Addendum] Besides removing items that don’t matter from the list, I have now added in more collections from my delicious bookmarks.
CSS and Code Design Tools
YAML Builder 
Easy to use YAML (Yet Another Multicolumn Layout) XHTML/CSS site layout builder.
960 Grid System
Streamline web design production workflow by using commonly used dimensions in grid layout format.
Sky CSS Tool
JavaScript CSS authoring app.
The Box Office
CSS formatting tool for wrapping text around images.
CSSTXT
Online CSS text style generator.
CSS Speech Bubbles
CSS based speech bubbles from Will Mayo.
izzyMenu.com
Free CSS menu builder.
templatr
Online tool for creating website templates.
dotemplate
Template site that allows you to customize templates before downloading them.
Typechart
Browse different typefaces and styles and grab the CSS of the ones you want.
CSS Superdouche
Strip unneeded content and redundant calls from your CSS, reducing its size and complexity.
Code Beautifier
Format and optimize your CSS code.
CSSFly
In-browser editing of (X)HTML and CSS.
CSS Drive CSS Compressor
Decrease your CSS file size and loading speed with this tool.
Clean CSS
Another CSS optimization tool for reducing your CSS file size.
CSS Redundancy Checker
Eliminate unused CSS selectors automatically as well as check for redundancy in your CSS files.
CSSround
Another tool to create rounded corners on your website.
TabCreatr
Create CSS tabbed navigation for your site.
List-u-Like CSS Generator
A tool to create list-based navigation bars.
Form Designs
StyleIgnite
Design snippets (CSS, HTML, and more) for contact forms, layouts, and more that you can use on your sites.
DevSnippets
Gallery of code snippets and examples shared by designers.
pForm
HTML form builder.
Form Style Generator
Create your own CSS-styled Web forms.
Graphics, Patterns, Buttons, Icons and FavIcons Generators
BgPatterns
Background pattern creation tool with live preview.
The Effect Generator
Create animated slideshows, buttons, and more with this tool.
ColorJack
A color scheme gallery that also explores color theory.
Cornershop
Get the CSS and images to put rounded corners on your website.
Artypapers Buttons
Customize buttons and collect them on your website.
Favicon Generator
Another free favicon generator.
favicon maker v1
A free, basic favicon creator that lets you create a favicon from scratch or an existing image.
favicon.cc
Another free favicon creator.
Stripe Designer
Create background stripes for your website.
Loader Generator
A tool to create loading spinners.
IconsPedia
Free, huge collection of icons.
Colours and Style Palette
ColourLovers
A colour resource that monitors and influences color trends.
The Color Wizard
Submit a color and this tool will bring back matching colors.
[ws] Color Scheme Generator 2
An easy to use color scheme creator.
Color Hunter
A color palette creation tool that lets you pull color palettes from images.
4096 Color Wheel
A color scheme generator that shows you Web-safe, Web-smart and unsafe colors.
colordb
Another color palette generator, though this one is much more in depth than most.
colorcombos.com
A huge library of color combinations.
ColorToy 2.0
A Flash-based color palette generator.
Accessibility Color Wheel
Check the readability of your background and text color combinations. This tool will tell you if there is enough contrast between the two.
Cymbolism
A color tool that includes information on what emotions and words are associated with different colors.
Instant Eyedropper
Grab the color code of any color on the Web with a single mouse click.
Design Galleries and Creative Inspiration
CSS Import
Gallery of beautiful, full CSS websites.
CSS Mania
Another gallery of almost 12,000 CSS website designs.
FullSingle
A gallery of really awesome single-page websites.
We Love WP
A showcase of WordPress powered websites (not just blogs).
One Page Love
Another showcase of great one-page websites.
Screenalicio.us
A Web design gallery with more than 10,000 screenshots.
The Best Designs
A huge showcase of Web designs and designers.
Pattern Tap
Design gallery of different website elements (headers, 404 pages, and the like).
eduStyle
A Web design gallery specifically featuring academic websites.
Designflavr
Design galleries for all sorts of artwork, including Flash and CSS websites.
View
Showcase of website that can be sorted by color or other criteria.
InspirationKing
A searchable gallery of websites for inspiration.
DesignerSource
A website design gallery that is browsable by topic or color.
BestWebGallery
Tagged website design showcase.
StyleVault
Another Web design gallery that lets you rate designs.
some useful stuff.