Useradministration on Apache/PHP/MySQL

Hello group.
I would like to offer our students a webplatform with A/P/M. There are 1500
potential users, so there must not be to much manual administration
involved. What systems are available, that more or less automates the
creation and deletion of useraccounts on a webserver? We (will) have all the
users i Active Directory, so some sort of username/password interaction
(LDAP?) would be nice.

Thanks in advance,
Carsten Keller