On June 15th & 16th, Northfield Yarn will be part of a southeastern Minnesota shop hop called YARNventure 2012. You can download the Northfield Yarn brochure here, and make plans with others by joining the YARNventure 2012 group on Ravelry.
The Shop Hop punch card can be found here: Punch Card. Print them one out and remember to bring it along on your YARNventure!
The full brochure for all of the Shop Hop locations can be found here.