I will second your suggestion. I've been grabbing all kinds of pngs from there in the Western motif, and what I haven't been able to find, I've been able to make requests and more often then not someone has what I'm looking for.

Also, Heruca is a great resource and a member of these boards and has a great application called battlegrounds that allows you to drop all those wonderful pieces into a gaming interface that allows you to move player tokens around and add sound effects, and resource material. I highly recommend it as well if your mapping is for gaming purposes.