Did you read my append and xbytor2 append. There are many Scripts that add some EXIF date to images. Most do it by adding a text layer. An action could use such an script to add the text layer then position and style the text layer. If you have many different size and resolution images files you need a script that will set a good font size for the image being processed. Such an action can be batched. You can search the web for these script or modify the one I posted for you.
A Photoshop script can even your default web browser on google maps for the image's location if there GPS info is in the images EXIF.
