The woodgrain-01.jpg has been taken from the JiGo 2.1.1 distribution and later modified.
The stone graphics were captured from cgoban1, which creates them algorithmically in a very pleasant manner, and then enhanced with The Gimp. I should just rip the algorithm, but the enhancement step is difficult to automate ;)
Sounds here were taken from opie, imaze and gnome-audio (and modified), with additional goban sounds by Robin Redeker.