Cryptography expert Bruce Schneier used to write his passwords down on a slip of paper and keep it in his wallet.

Today, he uses a free Windows password-storage tool called Password Safe that he designed five years ago and released into the open-source community. The desktop application lets users remember only one master password to access their password list.

But Schneier still recommends the paper method for people who don't have their computers with them at all times like he doe...