This action should work in all recent versions of Photoshop and Elements.
The "Rule of Thirds"
The "rule of thirds" has existed in imaging since the dawn of time; and quite a few programs have had a rule-of-thirds guide incorporated into their cropping functionality for quite a while. Surprisingly, Adobe only introduced it to their Crop Tool in CS5.
For everyone without CS5, I hope this little action will be useful:
(Mac users, you might have to Option-click the link to make it work.)
What does it do?
Cropping, in my firm opinion, is something that should only be done at the end of the workflow, when you have specific reason to do so. Arbitrary cropping early in the workflow can lead to difficulties later on. Therefore, this action is designed to be used with a specific output size in mind.
First, it prompts you to enter your desired output size. For example, if you were preparing an 8x10 print, you'd enter 8 inches by 10 inches at 300ppi:
If you were preparing a web proof, you could enter 11x15 inches at 72ppi. And so on. The PPI value isn't critical - all that really matters is the shape.
Then, it very quickly makes a rule-of-thirds grid and pastes it onto your image (on its own layer set to Soft Light mode) and enters Free Transform mode ready for you to move and resize as you wish:
Make sure you only resize the grid using the corner tranform handles, and remember to hold down the Shift key as you're doing so, to keep the correct shape.
Once the grid is sized and positioned to your satisfaction, press Enter/Return to commit the transformation.
Then use your Crop Tool in the usual way, positioning it around the edge of the grid.
Once you've cropped, just delete or turn off the grid layer, then sharpen and save your image ready for print or web. Easy!
If you have a question about this action, or any Photoshop question, please visit me at my "Ask Damien" Facebook page.
All content © Damien Symonds 2013