This map I've done following some amazing tutorials:

arsheesh's tutorials:
[Award Winner] Making Map Borders in GIMP

[Award Winner] Making Photo-realistic Trees in GIMP: A Mini-Tut

and RobA's tutorials:
[Award Winner] Using GIMP to Create an Artistic Regional RPG Map

[Award Winner] Simple Mountains in Gimp

Here is the result:

I am also making a technic (well, I think I am) to make fast and cool looking pseudo-random heightmaps, hope I can make a nice tutorial someday.

Feel free to use this map for any non-commercial pourpose.