960 Gridder is an excellent tool for any web developer/ designer that wants to easily align, match and/or lay out websites. You can either use as an integrated component to layout your websites or use it as a bookmarklet. 960 Gridder will automatically identify if jQuery is present at the website and if it is not, it will include it. It injects your website of choice and you can then work with this tool to help you out with whichever layout/design task you find it useful for. By default, it is set to work with 12 columns, 60 pixel wide columns with a 10 pixel spacer left and right of the column, making it a 20 pixel wide gutter (which actually is the ones this gridder renders).

More info: 960 Gridder

Source:→ Ajaxian