First Map.

[moutarde]

One alternative to the outer glow would be (in photoshop, don't know if it works the same in GIMP) to Select your text, then Modify-->Expand 2 or 3 pixels, then delete the terrain underneath it. Then you're left with legible text without unduly messing up everything else.

I would suggest a layer mask, rather than deleting though. That way if you need or want to move the text afterwards, you still have your terrain hidden away instead of lost forever