Aah, the d12 - a sadly underused and misunderstood die.
Unless you play a Barbarian weilding a Greataxe. Or you're dicking about with 3.5's Powerful Build (those dirty, dirty Goliaths and Half-Giants).
But, fear no longer, mightiest of polyhedrons!
The Dungeon Dozen is a cool little resource for GMs of every genre (though fantasy/dungeoncrawls seem to be a specialty), where the author creates fantastic little tables for everything from encounters, to moster characteristics, to NPC motivations - all using the humble dodecahedron.
Check it out!