Flight or airport activities to pass time

Just wondering what rituals or little things you do on your flight or when waiting for the plane to kill time. I know a lot of people drink or tour the airport shops. Being a bit paranoid I always size up the other passengers looking for possible psychos or terrorists :).Sleeping on a plane or in airports is usually impossible for me. I always have plenty of reading material and my own snacks. Any other ideas ?

If we fly frontier...which we like to do...they have direct tv...and it is free between Denver and PV...so I watch tv..otherwise I always bring 2 books with me...depending on the size of the book...between the flight time, and the layover...I can usually finish or just about finish a book each way...whatever is left I read while sitting under a palapa on the beach...or lastly, I have an mp3 player that I have downloaded songs to and I play that, have a drink and watch the clouds roll by...