Get a dynamic background grid image simply by using their URL as the background for a site you’re building. Very handy.
grids
Gridulator
"Tell Gridulator your layout width and the number of columns you want, and it’ll spit back all the possible grids that have nice, round integers… There are inline previews, courtesy of the canvas element, and when you’re all set Gridulator can crank out full-size PNGs for you, ready for use in your CSS, Photoshop docs, or what have you."