The Guardian published an interesting article where their reporter investigated how much information an identity fraudster could get about you from a simple airline stub, picked out of a bin near Heathrow:
"We logged on to the BA website, bought a ticket in Broer's name and then, using the frequent flyer number on his boarding pass stub, without typing in a password, were given full access to all his personal details - including his passport number, the date it expired, his nationality (he is Dutch, living in the UK) and his date of birth. The system even allowed us to change the information.
Using this information and surfing publicly available databases, we were able - within 15 minutes - to find out where Broer lived, who lived there with him, where he worked, which universities he had attended and even how much his house was worth when he bought it two years ago. (This was particularly easy given his unusual name, but it would have been possible even if his name had been John Smith. We now had his date of birth and passport number, so we would have known exactly which John Smith.)"
Actually, as outlined in comments on Bruce Schneier's posting about this article, you could practice using Google Images.
