If I see a spider in my house I'm generally content to let him chill out, if he's just hanging out on the wall or something. Wolf spiders not so much, since they don't build webs and are actively scurrying around. Those I'll kill. I picked up the habit of whistling "nearer my God to thee" (the song the band plays in James Cameron's Titanic as the ship sinks) while flushing bugs down the toilet. You generally have to antagonize a spider quite a bit to get it to bite you, or harm it in some way - accidental or not. Centipedes however are something I hate.