iGrid plots drawing grid right over your desktop, so you can use it everywhere, with any drawing application without any special plugins for different graphics applications. Just install and run iGrid and you'll see grid plotted over entire screen.

Grid presets allow you to choose one of the following grid for orthogonal:
1. Regular small
2. Regular medium
3. Regular large
4. Advanced small
5. Advanced medium
6. Advanced large

for axonometric:
1. 30 isometric projection
2. 1/2 isometric projection
3. 30 60 isometric projection
4. 45 45 "military" isometric projection
5. 7?42 0.5 NEN/ISO dimetric projection
6. 30 0.5 "chinese perspective" dimetric projection
7. 0.5 "side-view" dimetric projection
8. 0.5 "top-view" dimetric projection

and for handwriting:
1. Regular small
2. Regular medium
3. Regular large
4. School small
5. School medium
6. School large
7. Elementary school small
8. Elementary school medium
9. Elementary school large

You can change all the parameters of any preset to create your own grid. Just click the source preset you want to use as a base then click the "Custom" item in the presets list and change grid parameters.
Grid can be shown and hidden by click on the tray icon, but in addition you can define hot key for fast showing and hiding grid. Open Settings dialog, select the "Show/hide hot key" item and press the shortcut you want to assign.

The license of this software is Free Trial Software, the price is EUR9.00, you can free download and get a free trial.