Thanks for the info, azmmza! You'll find alot of information over in the NW forum on the BUMP Program. Basically, NW will take (most) other major carriers' tickets for travel on NW on day of departure if they have available seats.

In a few cases, NW agents may be able to access other carriers e-tickets, but this is usually not the case. This usually leaves two options: 1.) getting the other airline to "push" the e-ticket over to NW in the computer system (which most carriers appear loathe to do); or 2.) getting a paper ticket (can usually be an unendorsed ticket) from your carrier and taking it over to NW. If NW has seats available, they'll usually check you in and give you a boarding pass. On rare occasions, I've gotten a seat request card but have almost always (I think I'm something like 4 out of 5) ultimately been successful in getting onto the flight I want

It's a slick way for NW to pick up extra revenue and earn some customer goodwill on seats that would otherwise go empty. The program is unpublicized and can be very helpful (especially if you, like me, live in a NW hub city (MEM)).

Don't tell anyone about the program, though!