Update 12/2015: A Powershell version of this article is here.

There are several ways to do this, but the method I prefer to use is GET-QADUser command from the Quest Active Server Roles PowerShell module, as it will dump the information I want with a minimum of fuss.

  1. Start the ‘ActiveRoles Management Shell for Active Directory’ console
  2. Enter the following command string
    Get-QADUser -sizelimit 0 | Select-Object sAMAccountName, DisplayName
  3. and then press EnterSamAccountName    DisplayName
    DaggF             Fred Dagg
    CollinsP          Paul Collins
    SprouleK          Ken Sproule
    ReithP            Peter Reith
    SmithC            Coach Smith
    RookeM            Mike Rooke

Or if I want to dump it out to a CSV file, so I can look at it in Excel:
Get-QADUser -sizelimit 0 | Select-Object sAMAccountName, DisplayName | Export-CSV 'c:\temp\AllDomainUserNames.CSV'

To dump all the user details out, you could doing something like:
Get-QADUser -sizelimit 0 -IncludeAllProperties -SerializeValues | Export-CSV 'c:\temp\AllDomainUserDetails.csv'