I have a Photoshop Plugin, which is available from boxtop software's
photoshop plugin page called SimpLines. It makes great grids, either on
your image or on a layer. You can specify the spacing of vertical and
horizontal lines, and the color will be the foreground color, so you can
make that anything you want. the url is
"http://www.boxtopsoft.com/plugpage/".
It is a very small download and very cheap shareware, about $7, I think.
Real useful.
Larry Bullis
Skagit Valley College