function add_user_to_iis_group([Parameter(Mandatory=$true)]$username)
{
    $computergroup = [ADSI]("WinNT://localhost,computer")
    $admins = $computergroup.psbase.children.find("IIS_IUSRS")

    foreach ($member in $admins.psbase.Invoke("Members")) {
        $member_name = $member.GetType().InvokeMember("Name", 'GetProperty', $null, $member, $null)
        if ($member_name -eq $username) {
            Write-Host $username "already in this group."
            return
        }
    }
    $admins.Add("WinNT://$username")
}