Gumby 960 Grid Responsive CSS Framework
The NEW Responsive 960 Grid CSS Framework That You’re Already Familiar With.
BluCSS
Your best buddy when it comes to creating responsive layouts.
Golden Grid System
A folding grid for responsive design.
Skeleton
… a Beautiful Boilerplate for Responsive, Mobile-Friendly Development […] a small collection of CSS & JS files that can help you rapidly develop sites that look beautiful at any size, be it a 17" laptop screen or an iPhone.
Fit To Scale
«[…] The more I work with flexible images & grids and media queries, the more I appreciate what can be achieved. […]»