Nathan has a log book (or actually, quite a few by now) with all his flights in it. Most pilots do.
Our kids also have log books! We figured, with a Daddy-pilot and a Mummy-hostie, they just might get interested in flying when they get older, so it would be a nice thing to have then.
Ever since their very first trips, we have logged all their flights in these books. We write the date, flight number, departure and arrival airports and then on each flight we hand these books to the pilot who fill out the air miles and sign it. Sometimes they add little personal messages too, just for fun!
It's actually quite a nice little keepsake!
The trip after next, Lucas will clock his 100th flight!!! (And Linnea her 70th!) Not bad for someone who just turned five (and three!), guess we will have to do some celebrating!
(Edit: You can buy these log books on board British Airways, that is if they still do them. We modified ours a bit ourselves.)