You may have read about Cisco and Ford Motor Company using LDAP for product management. I know of a company that uses LDAP replication to keep its organizational data in sync between its headquarters in Texas and its ships at sea. In short, LDAP provides you with a standardized system for tracking the workers in your organization. This way, when a person is hired into the organization, a user account is created for her, and when she leaves the organization, her account is closed. Your number one security headache has just been cured.
Some systems require a digital certificate or fingerprint.
The most secure systems usually require both a password and a digital certificate or fingerprint. A common security problem in organizations is that there's no way to match each account on the system with a real person. The EUID becomes a user's ID on each system he uses. And this is the crucial first step toward single sign-on. When you change over to an LDAP server, you can concentrate on improving authentication in other ways as well.