I like going to the Curve Lake Reserve south of Buckhorn. The Whetung Centre is an art gallery and native craft store. Lots of authentic stuff from all over North America. Cheap gas too on reserve.
Also take a drive to Bobcaygeon for some shopping and get a cone at Kawartha Dairies factory store.
Peterborough Farmers Market on Saturday morning on Landsdowne.
Lots of bike trails in Peterborough.
Take a run up to Algonquin for a hike and check out visitor centre.