Now this is a pretty basic tutorial that will explain how to use the Bump Map Plugin to create a very neat effect. Some of you may know what a bump map is and some not. This is for those who don't!
Bump maps are a Grey scale layers that are used with the Bump Map plug in for Gimp to create the effect of a raised or lower section on another layer. It creates a 3d type effect. Kinda like embossing something, but the over all effect is different. Sounds way more complicated than it is!
OK here we go!
Steps
1: Download this image (Thank you phillFX). This is the base for the dog tags!

2: Use the Rotate tool Shift+R on the keyboard. Enter a value of 124.84 and click rotate
3: The Dog tag image should now be pretty close to level
Now we create our Bump Layer!
4: Select you Typing tool or press T on the keyboard.
Typing tool Setup Font: Courier New Bold (Thanks Beren)
Size: 40
Select Anti aliasing only
Color: Black HTML #000000
5: Now type out whatever you want I used Droz928
6: Select your move tool or press M on the keyboard. Now move the text where ever you want!
7: Type what ever you want to show up on the dog tag!
8: Once you get what you want typed out merge all the text layers together.
DO NOT MERGE TO THE DOGTAG LAYER!9: Right click on the text layer and select layer to image size
10: Right click on the Text layer and click alpha to selection
11: Invert the selection. Select you paint bucket tool and fill the selected area with white!
12: You should now have black text with a white background
EXAMPLE
OK now the fun starts!!!
13: Turn the visibility off on the bump layer and select your dog tag layer
14: Select Filters>Map>Bump Map
Bump Map SettingsYou can play with any of these settings. For a full description of what each setting in the bump map plug in does check this out.
Bump Map Plug In Help1: Click the little down arrow and select your bump layer
2: Select Spherical
3: Elevation 50
4: Depth 2
You should now have Dog Tag layer bumped.
15: Delete the Bump Map Layer
16: Now you can rotate the layer any direction you want.
Here is my finished Dog Tags GBD style

I hope this was kind useful and once again thank you philFX for the awesome idea!