The Janus Authenticator is client/server scheme to allow web applications to authenticate users via a remote authenticator. The initial client, server, and login apps are written in PHP, and direct communication between the two will be done via XML-RPC.
...It includes a schema independant editor, a schema viewer and some pretty Views of the data. (And an easy way to create your own custom views). Directory Manager requires an LDAP v3 server.