I really enjoyed Kate Wilhelm's Storyteller which won the 2006 Hugo award for best related non-fiction. It was both an entertaining writer's guide and history of her time teaching at the Clarion writer's workshop.
Small Beer Press, the publisher of Storyteller is currently selling copies of it for just one dollar to clear out their warehouse. It's a great bargain and they have several other chapbooks and anthologies similarly discounted. You can't beat that price for such a great book so I'd recommend grabbing it while they still have some.
