Well, the brushes I used for forests and mounts are by Wag, so you can just download them here.
http://www.cartographersguild.com/showthread.php?t=4571

And the big parchment canvas was found on Google images. Alternately, you could make your own, I'm sure there is a fine tutorial around here somewhere.

The smears and stains are also brushes that I found on the internet, though I don't remember where exactly. Probably on www.deviantart.com.

And for this map, I used GIMP.