My organization is rolling WSS out to the enterprise. They do not
like the way users are added to the sites. They would like the
ability for users to type in a name or part of a name and have
results come back from AD.

I know this part can be created easily enough but can I use the
information to populate the appropriate fields in the Add User
screens; email address, domain\user name, display name?

We do not have Exchange nor do we have SPS.

One of the issues is that we have users from multiple domains that
need to be added.

Has this been done by anyone? Can anyone point me to some resources
that may help?