SaaS LDAP/directory service?

Question

I know that my Googling skills are failing me because there must be something like this: a simple, easy-to-use remotely hosted directory service (and even better, exposes the user directory through several different interfaces, and SSO).

Do you know of one and/or have one to recommend?

I am looking at Atlassian Crowd - http://www.atlassian.com/software/crowd/overview - which comes close with the pluggable interfaces, but it does not implement LDAP. It can only connect to an existing LDAP server.

Answer 1

This has already been discussed on ServerFault, and I think the answer given here may be a good starting point for your search. It lists Symplified, Entic.net and eApps.