I have given them a few times to very helpful F-A's and a friendly phone reservations agents (who was one of the funniest people I've met... even funnier than JAWS! I know I'm going to hear about that last remark!)
I've never heard any response from those I've given them to... but I don't care. If they can gte something (a gift or even better a raise or cash bonus) then I feel better.
CATMAN