I had registered for a NW promotion that offered double miles whenever connecting through Memphis. Then I looked at expiration date and said...well, I will never use that. Oh well.

Last week our flight from Seattle to MSP was cancelled and we had to stand in line to rebook. They rerouted us home through MEM instead of MSP. When I checked my statement I found 2370 bonus miles for going through Memphis. (I had forgotten all about this deal.) It never hurts to sign up for stuff, even if you think you won't use it!