Placehold.it – Quick and simple image placeholders

How does it work? Just put your image size after our URL and you’ll get a placeholder.

Bootswatch – Free themes for Twitter Bootstrap

Free themes for Twitter Bootstrap.

Themes for Twitter Bootstrap – WrapBootstrap

Premium themes and templates for Twitter Bootstrap.

How To Use CSS3 Media Queries To Create a Mobile Version of Your Website

CSS3 continues to both excite and frustrate web designers and developers. We are excited about the possibilities that CSS3 brings, and the problems it will solve, but also frustrated by the lack of support in Internet Explorer 8. This article will demonstrate a technique that uses part of CSS3 that is also unsupported by Internet ...

SASS /LESS/ Color Variables

http://sachagreif.com/sass-color-variables/

A collection of inspirational websites using media queries and responsive web design. Curated by Eivind Uggedal

http://mediaqueri.es/

960 Grid System

“The 960 Grid System is an effort to streamline web development workflow by providing commonly used dimensions, based on a width of 960 pixels. There are two variants: 12 and 16 columns, which can be used separately or in tandem.”

Twitter Bootstrap

“Sleek, intuitive, and powerful front-end framework for faster and easier web development.”

Gumby 960 Grid Responsive CSS Framework

“Gumby Framework was built to be the most maleable grid framework you’ve ever used while still maintaining the familiarity and ease-of-use of the grid you’ve always used.”

Variable Grid System – Generate CSS grid templates based on ‘960 Grid System’

“The variable grid system is a quick way to generate an underlying CSS grid for your site. The CSS generated file is based on the 960 Grid System.”