Another suggestion from auh2o girl, soon to be registered on FlyerTalk:

Automatic notification of a delayed flight to the person at the phone number of your choice, i.e. secretary, office manager, spouse, person meeting your plane, chauffeur, etc.

Airlines would set this up for you on their computers, if you're a frequent flyer. You
need the option to add or change the numbers called via computer. Changes to the telephone numbers(s) could be made just prior to boarding and would be input into the airline computer system. Whoops, on second thought, this might not work.