DO-AHEAD TIP: Marinate salmon for 15 minutes (see recipe).
Preheat outdoor or indoor grill to MEDIUM-HIGH or oven broiler. Place salmon fillets in a glass baking dish.
In a small bowl or cup, combine melted butter and lemon juice; pour over salmon; marinate for 15 minutes.
Grill/broil salmon for about 4 minutes per side (depending on thickness) or until just opaque, brushing with lemon marinade occasionally. Salt and pepper salmon while cooking.
Sprinkle fillets with chopped dill and serve lemon wedges on the side.