I agree with TI, Coal is common enough and easy to find. It has value as a fuel. But things like gold or diamonds would be worth a lot of coal.
I think we should come up with some kind of "Cost Table" that says x is worth y of z.
My main opposition to using gold is its "value" would be too high to buy lesser items in realistic quantities.
Saying that, I think the "bank" should be able to store types of resource - cobble, wood, dirt and sand excluded - as everything has some kind of value.
I would also like to see the continuation of the "here, have this, i got more" as that it the TOG way!
"I am a Pantera's box you do not want to open" - Mr. Furious