Nice banner. I like the stone look of the letters. I'll use it if you make it smaller.
Heck, I should make an html version of the readme and include it in that. I do need to make some sort of a strategy guide.
Amber - luxury
Timber - ships larger then canoes/outrigger cannoes, pallisade, turret, sawmill (maybe some others, that's all I can think of off hand)
Olives - olive press
Sacred Ruins - Oracle, League
Lion - Lion Warrior
Bear - Bear Warrior
Kracken - just for looks
Giant Octopus - just for looks
Sheep - fold improvement
Walrus - no function
Shellfish - no function
Oysters - no function
Pigs - sty improvement
Caribou - no function
Moose - no function
Copper - copper foundry, used with tin for "armoured" units
Stone - lots of improvements, paved streets, amphitheater, colosseum, wall, tower, ...
Clay - kiln improvement
Marble - luxury
Roots - root field, root farm, root plantation
Beans - bean field, bean farm, bean plantation
Fruit - no function
Reeds - no function
Slaves - appears were goody huts were, used for slave unit, slave auction, slave galley
Salt - luxury
Gems... - luxury