Take a Hike
The tourist office sponsors 6km (4-mile) guided walks through the countryside on weekend afternoons March through October, costing 20€ per person (walks occur if at least two people make reservations). Because the country edges right up to San Gimignano's walls, you could also easily set out on your own to wander with a good map -- the tourist office sells an excellent 1:25,000 map for 7€, marked with suggested hikes and walks, or you can pick one up from any local souvenir stand.
Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.