In a small bowl, mix together the maple syrup, tamari (or soy sauce), garlic, and optional ginger. I sometimes add a few grinds of the pepper mill, too.
Place the salmon in a shallow glass or ceramic baking dish that is just large enough to hold the salmon. (This will keep more of the maple syrup mixture around the fish; line with parchment or foil for easy cleanup.) Pour the mixture overtop. Marinate the salmon at room temperature for 30 minutes, using a spoon to drizzle the tamari mixture over the top once or twice.
Meanwhile, preheat the oven to 400 degrees F. Place the salmon in the preheated oven (with the marinade) and bake, uncovered, for 15 – 20 minutes, or until just barely cooked through the center.