When you travel, it's easy to toss out your old boarding passes the second you get to your destination. Resist the urge! Keep your boarding passes for a few months after your trip is over. You can use them to pick up frequent flier miles retroactively if you want to create a frequent flier account after your trip. Also, if you need to complain to the airline about something, you'll need your complete ticket information that can usually only be found on your boarding pass.
