ftp://ftp.microsoft.com/PSS/Tools/Exchange%20Support%20Tools/ADModify/

Contains the final 1.x release (ADModify 1.6) and also the first ADModify.NET release.

[EDIT:  Please visit http://ADModify.NET for all releases of ADModify, do not use ftp.microsoft.com or gotdotnet]

ADModify.x is a tool primarily utilized by Exchange and Active Directory administrators.  ADModify 2.0 (aka ADModify.NET) was rewritten from the ground up using Visual C# .NET 2003.  When benchmarked against its predecessor, version 2.0 made the same modifications in less that half the time.  Its new feature set allows administrators to bulk modify any AD attribute from any AD partition with almost limitless flexibility.  Administrators will also find that they are no longer restricted by the attributes hard coded into the tool, as ADModify now contains the ability to modify any attribute just simply given its name and value.  ADModify is also no longer restricted to literal values; it is now possible to dynamically build values based off of current AD attributes.
 
Logging and Error handling has also improved dramatically.  All logging is now done using XML, making it much easier for administrators to manipulate and store the data and even take advantage of features such as Undo.  Keeping with the Windows 2003 initiative that everything that can be done in the GUI should be available via command line, a command line version of the tool that contains all of the same features is included as well.

It is worth noting that ADModify.NET requires the .NET Framework.  It also is worth noting that it will not run across a network drive.

More information on ADModify.NET is to come on the Exchange Team Blog:  You Had Me At EHLO... which is at http://blogs.msdn.com/exchange/