LDAP Information on the Internet
LDAP FAQs and Presentations
A System Administrator's View of LDAP. A system administrator's perspective on what you'll need to reap the benefits of using LDAP: a good understanding of what LDAP can and cannot accomplish, some familiarity with LDAP basics, and ideas on how to make the transition to LDAP.
Steve Kille's (of Isode) talk "Why Do I Need a Directory When I Could Use a Relational Database?"
Mark Wahl's (of Innosoft) LDAP FAQ.
Mark Wilcox's LDAP FAQ.