San Pedro might be one of the coolest little towns I've ever been to.
It's very poor; but the people are really nice. I suggest making conversation with any of the store owners or farmers walking along its roads. You may have to know Spanish; but surprisingly many of them speak a bit of English.
For essential San Pedro Dining go to Elvis's. They floors are sand, the drinks are all natural and the food is quality.
If you're in San Pedro it's most likely you're there for the diving. Dive as much as you possibly can (but still being safe) because it's some of the best diving along the Caribbean coast of Central America.