Over the past few years I've been using Google Mail for my personal, non-work related email.  Surprisingly, because of the rise of Social Media such as Facebook, the amount of email I receive to this account is quite limited.  Most of it being alerts from other sites.

A while ago, when logging into Google Mail I was greeted with a message across the top of the page: "Thousands of on-line accounts are hijacked every day. If you re-use your Gmail password on other websites, change it now"