I have always had peanut butter sandwiches as a side item with chili. It was always served that way in school, and my parents served it that way at home as well.
I've recently discovered some people apparently find this practice very strange (my wife included).
I eat my chili with a dip or two of peanut butter IN it. I always tend to get a reaction when I make my bowl. I simply hand them a spoon, give them a bite, and hand them the bottle of peanut butter.