pam and other authentication methods

[Benedict Verheyen <linux4bene@pandora.be>]

Today i read that Slackware doesn't use PAM by default because of some
of the leaks that pop up now and then. I was wondering what other type
of authentications there are on Linux and how easy/difficult they are to
set up.
For instance, if i would now like to change the way users are
authenticated, how would i do that.
Any info on this?

What methods are good for providing 1 central repository of
authentication stuff os that you don't need to spread around passwords
and thus end up with having to change several sources when a user is
deleted for instance.

Regards,
Benedict