Thinly slice half the jalapeno pepper; seed and finely chop remaining half. In a medium bowl combine chopped jalapeno pepper and sweet pepper; set aside.
Place corn on the rack of an uncovered grill directly over medium heat. Grill, turning occasionally, for 10 to 15 minutes or until crisp-tender. Transfer corn to a cutting board; cool slightly.
Meanwhile, rinse salmon and pat dry; sprinkle with salt and black pepper. Add to grill. Grill 4 to 6 minutes or until fish flakes easily when tested with a fork, turning once. Cover salmon to keep warm. Cut corn from cob. Add to chopped peppers with 1 tablespoon of the barbecue sauce, the oil, 1/4 teaspoon salt, and 1/4 teaspoon black pepper.
Serve salmon with corn relish. Top with remaining barbecue sauce and, if desired, fresh herbs.