Favorite roads, central/northern IL

I am looking for fun roads to drive around north/central IL and wondered what everyones favorites were. There's a great eight mile stretch of serious twisties on IL 71, through Starved Rock State Park west of Ottawa, but that's about all I know. Haven't taken the new gti on it yet, but I sure enjoyed hitting it in my Pop's Boxster. :headbang:
So what are your favorite roads and why?

cherry valley road, between dekalb and rockford. its twisty and a beautiful drive, most fun on a crotch rocket. only like 20 mins long though.