ADModify.NET tool rocks!
I have seen this blogged and in newsgroups for over a year, but had not really played with it until recently. The hellomate.typepad.com blog by Meirick, Hobson & Lefkovics has had this blogged for quite some time (those guys rock, too!)
Anyway, Microsoft's PSS group has created a tool called ADModify.NET (formerly just ADModify) that is awesome. You can make a lot of bulk changes to the Active Directory from a nice GUI interface without having to learn how to use LDIFDE or ADSIEdit. I am totally impressed with this utility; it has made my life a lot easier several times. I am particularly happy with the ability to use it to REMOVE extra SMTP addresses, such as addresses that were used during a migration.
The latest version of ADModify.NET is 18.104.22.168645. It includes not only the bulk change abilities, but the ability to 'undo' changes since all changes are logged to an XML file prior to being made. You can also import mailbox rights for Exchange 2000/2003 mailboxes.
You can download this tool from Microsoft's FTP site.
Use this utility with caution. With great power comes great responsibility.