Would you pay for legroom?

If you prefer an aisle seat when you fly, you might have to pay for it on your next flight on Northwest Airlines. The carrier started a program last month allowing economy-class customers to reserve certain upfront aisle seats and exit row seats on domestic flights for a $15 fee. Travelers can reserve these seats online 24 hours before the flight, except for high-mileage frequent flyers, who can reserve 36 hours in advance.