Two Things
 

#1. I read about these "challenges" what are they and how does one go about starting one?

#2. I have noticed that sometimes if I use Expedia or Travelocity, I can find Continental Flights ticketed on Northwest Tickets that are cheaper on the same route as tickets ticketed on Continental. However, I am never able to find flights on NWA operated by Continental. Is this an Expeida/Travelocity anomaly or am I doing something wrong?

#1: The "challenge" was a targetted promo last fall "Fly X flights between to the selected cities listed below and qualify for Yyyyy Elite status through February 2004." The promo ended November 15, and if you weren't specifically targetted, you were not eligible. (AA has a similar concept which is available to anyone anytime. See the AA board for specifics.)

#2: If I am not mistaken, CO and NW each have a set number of seats in each fare bucket on codeshared flights, so fares and availability may not always match. As to why you cannot find CO-operated flights with NW codes on those engines, I have no clue.