[CentOS] Simple shared authentication method

Hi all,
I'm setting up an old server to became the core server of our local lug and I'm 
on trouble choosing an easy yet powerful method for authentication.
I think it would be nice to have a single method for authenticating local 
accounts, email, joomla and so on, and to be able to add another server and use 
the same method in the future.
I am looking now at openldap but I start thinking it's too complex for the task 
of single sign on... or at least I am missing an easy graphical tool to setup 
just users and passwords (ldapbrowser and directory_assistant aren't working, 
and I don't have too much time to spend on learning command-line tools).

Does anyone have a suggestion for an easy Single Sign On server?

Tia

Lorenzo Quatrini

p.s. Of course all the above under CentOS 5 ;)