tuxgeo
Adventurer
Thanks for all the suggestions guys. I think we've got all the colors covered.
I can't really do metallic colors. I use a laserprinter and while there are CMYK values for silver and gold it's not particularly shiny.
What about iconic images? What would be the single defining image of each class?
Barbarian - A club.
(Or a bearded face showing only bridge of the nose and below.)
(Brains don't count.) (The eyes ("ayes") don't have it.)
Bard - A lute. (Nothing else compares.)
Cleric - A book and a candlestick, the second laid atop the first.
Druid - A sickle.
Fighter - A mailed fist. Or the Hennessy "BRAS ARMÉ" design:

Monk - A robe tied with a rope belt.
Paladin - A golden oar. (A golden "or" -- or shield.)
Or a warhorse and a lance; or one or the other.
Ranger - A manger.
(. . . alright, that was unworthy of the question.)
A sturdy, high-topped boot suitable for Long-Striding.
Rogue - A question mark. Better yet, a dirk-and-a-smirk.
(You'll probably want to go with "cloak-and-dagger," though.)
Sorcerer - A wavy dagger or a lightning bolt. Something swerving or jagged.
Wizard - A wand emitting twinkly stars.