This has so many security and design concerns it's not even funny. Everyone has already said so in this thread already so I won't add to that, but I do want to

This has so many security and design concerns it's not even funny. Everyone has already said so in this thread already so I won't add to that, but I do want to add an even better solution. Add a remember me checkbox that when checked sets a cookie that you can use to identify the person with later. When the user gets to the login, he's presented only with the option to enter his password, and a link to login as a different user. Single input element without the security concerns.