Saw this spider around 7:00 PM central time. In Tomah, Wisconsin. Tomah is about 100 miles west of Madison. Found the little guy in the bathroom, just after a shower, haha. Sorry if the picture appears a little small.
Looks like Herpyllus ecclesiasticus, the Parson Spider, so named for the light colored pattern on the abdomen reminiscent of the clergy cravat worn some years ago. I'm not one of the experts here, so it's a good idea to check back for confirmation, but I'm fairly confident of the ID. Meanwhile, you can check out this link: http://bugguide.net/node/view/2041 for more information and additional pictures.
These spiders are ground hunters, not spinning a web to capture prey, and they are considered not dangerous to human beings with the exception of unusual allergic reactions. They are good pest control, and easily relocated outdoors if you prefer not to have them in the house. They're very fast, by the way, if you try to catch them, so good luck.
I personally dislike the little guys, mainly because I do get a slight allergic reaction to them and occasionally I will get bit. They have a page on here about them: http://www.spiders.us/species/herpyllus-ecclesiasticus/