Quoth Mr Hero
Me: I can, but it's going to require a username and password. You're trusting me with very sensitive information.
Actually, you don't need any of that. All that is required, usually, is the confirmation number and the passenger name.
They don't worry about someone else "stealing" someone's boarding pass, because you have to have ID to match to get to the plane and you can print as many copies of a boarding pass as you feel like.
This is probably why one of the NY SF/F cons is held in an Escher like hotel (walk on an even level and end up 2 floors up!).
There is a hotel that they have conventions at in San Jose that has a half-floor. You have to go to the floor above and then go down to it to get to it. It's kind of fun to direct people on how to reach that particular level, since that's the level that most of the panels are held on.