An on-line companion to the book Thinking with Type by Ellen Lupton that contains a section on single-column, multi-column and modular grids.
An article by Italian designer Andrea Peltrin on how to effectively use grids for web design.
An online grid generating tool that pumps out the CSS source code as well as a downloadable png file of your grid.
NineSixty is a Drupal theme that is based on the 960 Grid System.
UK based creative agency, DixonBaxi, has just launched a new site designed on a beautiful grid.