The 115-year-old Catedral de Santa Bárbara facing the town square (parque central) features an intricately carved wooden altar with painted statues of saints. At the time of writing, the park, unfortunately, was completely closed off, presumably for renovations.
Just outside of town are two balnearios (swimming holes) in rivers coming off the mountain, called La Torre and Santa Lucía.
A visit to the long-abandoned Castillo Bográn in the hills above Santa Bárbara [1] is a pleasant way to pass the day. From the square, look for (or ask any local to point out) the castle, visible on a ridge southeast of town. The castle is four kilometers from Santa Bárbara on a dirt road leading to the village of Las Crucitas.
Pickups occasionally drive the road and will give you a lift for a few lempira, or you can walk it in one or two sweaty hours, depending on your pace. Up close, the deserted castle is not as impressive as it looks from below, but the views are majestic.
Links:
[1] http://www.moon.com/destinations/honduras/central-honduras/santa-barbara-and-vicinity/santa-barbara