I was keeping "Zen Flesh Zen Bones" in the bathroom for a while, now it's Pema Chodron's "Comfortable with Uncertainty." Jokes about being one with the void aside these are both broken into short chapters, about 5-8 minutes worth of reading - very toilet friendly.
Last night I read Chodron talking about the lojong slogan "Abandon all hope of fruition" and I have thoughts mostly about art to put down later.