@Ddude: You just copy the sprite onto another layer, do like alpha to selection or whatever the GIMP version of selecting all the pixels are (I haven't used GIMP in so long...), fill with black, flip it vertically, shorten it to about 20%, skew it however you will, deselect it, blur it until it looks nice and shadowy, and then (the step I happened to forget in this panel) lower the transparency to about 75%. Boom. Shadows. @Nup: Will do.