LDAP and Microsoft's MAD
In order to test using OpenLDAP with Microsoft's Active Directory (since MS insist on using Microsoft in every product name acronym, I will too, hence MAD=Microsoft Active Directory), I built a test server with win2k3 in it's own subdomain, ads.mydomain.pri. The server is authoritative for this subdomain.
One of the first uses for this was developing a script to extract SIP: attributes from the DN: of all the users in my OU.