Cook pasta in generously-salted boiling water until al dente according to package instructions.
Meanwhile, pulse together arugula, garlic, 2/3 cup pine nuts, Parmesan and lemon juice in a food processor until combined. Slowly drizzle in the olive oil while continuing to pulse the pesto until it is incorporated.
When the pasta reaches al dente, drain the pasta. Then immediately toss with pesto, and remaining pine nuts. Serve immediately, sprinkled with extra Parmesan.
This pasta would also be delicious served with grilled shrimp or chicken.