If you're feeling energetic, climb up to the area's highest viewpoint. The panorama from the top of the Beacon stretches across most of Cornwall on a clear day; look out for the dark tors of Bodmin Moor to the east and the distinctive summit of Carn Brea in the west. It's just over a mile's walk (about an hour) from St Agnes town, and fairly well signposted from the village square.
Downloadable PDFs at www.stagnes.com detail several circular routes.