Social engineering doesn't always take a lot of skill or hard work. As a result of that, a UK bank recently exposed private details of 75,000 accounts. When requesting a copy of her statement, a lady received significantly more, a novel's worth of account details:

Stephanie McLaughlan received the mother lode, which comprised 500 pages containing 30 accounts each. Details included account numbers, withdrawals and other transaction information. The Netherkirkgate mother of one returned the booty and reported the blunder to bank officials.
How exactly do you accidentally mail 500 pages? It's beyond me, and apparently beyond the bank:

A spokesman for the bank said officials are starting an investigation into how the incident happened. A spokeswoman for the Financial Services Authority declined to comment on the matter...
Whoops. With all the problem we have with identify theft, you'd think a bank, of all places, would be a little more on the ball.