I have been working some more with Zend Framework at work and I needed the Zend_Auth to login users the Zend_Auth_Adapter_Db_Table seems obvious to use only is not very flexible, you cannot use any extra columns in your table to authenticate users.
My solution was to write a Zend_Auth_Db_Select adapter to authenticate against a Zend_Db_Select object so you can write your own query to validate against.
I have also added a way to remember the user and by default only use a session. It did not seem clear from the manual, but Zend_Auth will remember users with a cookie by default. read more