Noupe offers up a complete guide to techniques and tools for designing web layouts with grids. Includes basic information about grid design, links to more articles on specific aspects of grid-based design from other sites, links to all of the CSS grid-based layout frameworks I've heard of and a few that are new to me, and showcase of sites.
Via @zakiwarfel
http://www.noupe.com/design/ultimate-guide-to-grid-based-web-design.html