If you live in Illinois and you love the little histories behind names, Edward Callary's Place Names of Illinois is the book for you. For example, my father and mother live in Geneva, which I was surprised to learn was originally called Herrington's Ford - that finally explains all the Herrington toponyms around there! Toward the end of the book (pg. 389), Callary puts out a public plea: there are fifty places where the history behind the name is unknown. If you have roots in Illinois you should take a gander at the list, maybe you can help Callary out in the name of science. Maybe next time I visit my parents, I'll stop by one of these townships nearest them to help them out.
Here is a link to the list (click me!)