What Else Is There Besides OpenLDAP?

The Stunted Leech asks: "I am trying to develop an LDAP interface to an existing customer database and would like to implement a simple LDAP listener that could be queried from e-mail clients. Before everyone suggests importing the data to OpenLDAP or developing a back-end for it, let me just say that it isn't very feasible: I'm the only person assigned to the project, and my company doesn't have the time or hardware resources to maintain an LDAP server. So I'm looking for very simple implementations of LDAP servers, preferably in a scripting language like Perl or Python (we use Perl for CGIs and wxPython for GUI front-ends). I've come across a couple of Java-based ones, but they seemed overly complex - all I need to do is retrieve a contact's e-mail or phone number from our database. Pointers to any sort of simple LDAP servers are welcome, even if they do little more than return the same result to all queries."