Here's something I just came up with.
[img]http://www.daplayazclub.com/uploads/dogtag_final.jpg[/img]
First, draw out the overall shape of the tag with the pen tool. Turn on the grid and grid snap so you can get it symmetrical. Fill the space with a solid gray. Then draw out the notch, and use the eraser for the punched hole. If you need help, read this:
http://www.gurusnetwork.com/tutorials/p ... intro.html
Fill the dogtag space with a brushed metal texture, like you can find here:
http://www.elated.com/tutorials/graphic ... hed_metal/
Duplicate the brushed metal layer, Ctrl+Click it in the layers palette to select it, and go to select > modify > contract (2 px). Invert the selection, and run plastic wrap on it a couple times. Set this layer to color burn.
Put some lighting effects and a drop shadow on the lower layer to give it some life.
Add the text. Use gray Courier, and use the pillow emboss setting in layer styles and set the layer to lighten.
Adjust the brightness/contrast anywhere you want, and then you're done.