There are some interesting stats here - Survey Reveals How Stupid People are With Their Passwords - including :
http://www.emailquestions.com/email-articles/97-why-you-need-strong-passwords-protect-them.html
- 4 in 10 respondents shared passwords with at least one person in the past year
- 75% of people use the same password for Social Networking Sites and their email accounts
- Young people are 3 times more likely (12% overall) to share a password in a text message
- 86 percent do not check for a secure connection when accessing sensitive information when using unfamiliar computers
- Almost half of Facebook users (47 percent) use their Facebook password on other accounts and 62 percent of Facebook users never change their password
http://www.emailquestions.com/email-articles/97-why-you-need-strong-passwords-protect-them.html