Some folks may recall this from using the Winternals product,..
ADInsight is an LDAP (Light-weight Directory Access Protocol) real-time monitoring tool aimed at troubleshooting Active Directory client applications. Use it’s detailed tracing of Active Directory client-server communications to solve Windows authentication, Exchange, DNS, and other problems.
As long as I'm going on about AD tools - might as well have a look at AD explorer:
IMO the cool part of AD explorer is:
AD Explorer also includes the ability to save snapshots of an AD database for off-line viewing and comparisons. When you load a saved snapshot, you can navigate and explorer it as you would a live database. If you have two snapshots of an AD database you can use AD Explorer's comparison functionality to see what objects, attributes and security permissions changed between them.
And last but not least - AD topology diagrammer thingy-
The Microsoft Active Directory Topology Diagrammer reads an Active Directory configuration using ActiveX Data Objects (ADO), and then automatically generates a Visio diagram of your Active Directory and /or your Exchange 200x Server topology. The diagramms include domains, sites, servers, administrative groups, routing groups and connectors and can be changed manually in Visio if needed.
Some of these tools are new - some old.. but all worth looking into and could prove a valueable tool when needed.