Preheat broiler. Combine first 5 ingredients in a small bowl. Cover and chill until ready to serve.
Cut salmon into 18 (1 1/2- x 1 1/2-inch) pieces, and place on a lightly greased aluminum foil-lined baking sheet. Brush with chili sauce. Broil 3 to 5 minutes (for medium) or until desired degree of doneness.
Spread 1 teaspoon wasabi-ginger aïoli on bottom of each bun. Top with salmon, a dollop of aïoli, arugula, and top buns.