Yes, as noted, great surf in El Salvador.
I lived there for a year and am sad to say that I didn't explore as much as I wanted to.
It is a beautiful place that is largely undiscovered by gringos. In one day's drive can go from the beach to the volcanoes and see notable cultural spots and villages along the way. The country has a rich history based around the civil war.
In San Salvador I would recommend the civil war museum and romeros house (priest who was killed in the war)