Had a rat snake in the house I was living in this past school year. I'm fine with snakes for the most part...except when they suddenly appear in your dark hallway. Luckily as I took off down the hall in one direction the snake took off down the other way.
I never did find him, my roommate did though. Tipped off by a horrible stench when he came home from vacation (no one had been in the house for about two weeks at the time) he found the thing rotting on a mouse trap along with two dead mice that he followed into the house. Great fun!