Good security policy is to have a different password for each password-protected resource, but even a moderate internet user can have accounts on tens or even hundreds of websites. Most people's solution to this is to pick a decent, strong password and use it everywhere. Unfortunately, different sites have different requirements - minimum lengths, capitals, numbers, sometimes even non-alpha-numeric characters. Often, it can be frustrating trying to remember what variation of your password to use to log into a site. Eventually, OpenID or similar will solve this problem, but in the meantime, this website is designed to help.
This site makes no recommendation about how to manage your passwords - there are other sites that are far better at that.
I started building this site as a wiki, but that was a mistake. Soon I'll get round to re-implementing it in PHP.
You can email me if you want to.