Northwest WorldPerks members can choose to “SuperSize” their bonus miles when purchasing flights through nwa.com. For a mere $20 you can get an additional 1,000 miles when flying Northwest Airlines, Northwest Airlink or KLM Royal Dutch Airlines. The offer is available to residents of the U.S. or Canada only, through Dec. 31, 2007. You must purchase your SuperSize miles before your roundtrip flight. At 0.02 cents a mile, the cost is quite good. But don’t expect the bonus miles to help you make elite status — they won’t.