GIMP :: How To Add A Border To Text

1. Get your image you want your text on. For this tutorial, I just have a basic wood background.

2. Type your text. check the box labeled "anti-aliasing" for a smoother transition. For the purposes of the tutorial, I chose a very simple white text, but you can use whatever you want.

3. Go to Layer > Layer boundary size. You'll want to have a boundary that is about double the current size, or so. You probably won't need that much, though. Unless you're trying for a really big border. :P
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4. Go to Layer > Transparency > Alpha to selection on your text layer. This will put a selection around your text. Then go to Select > grow. Depending on the size of your text, and your desired results, you may have to play around with the amount for a bit. For this tut, I chose 5 pixels.

5. Make a new transparent layer, and place it underneath the text layer. Select the color you want your outline to be as the foreground or background color. I chose black. Then go to edit > fill with bg/fg color, whichever has the color you want your outline to be. Then go to select > none, and there you have it!