Grid Slicer is a useful Photoshop Script that divides image into grids with given Width and Height division values.

Installation: Unzip downloaded file. Put "Grid_Slicer.jsx" file into the Photoshop Presets Scripts-folder. Restart Photoshop After restarting Photoshop Grid Slicer script should be available under File Scripts and can be assigned to a Keyboard Shortcut directly or recorded into an action for speeding things up.