<?php
error_reporting(E_ALL | E_STRICT);
ini_set('display_errors', 1);

require_once 'app/Mage.php'; // please include full path of Mage.php

Mage::app('default');

$customer_email = 'test@magentotutorial.in';  // email address 
$customer_fname = 'firstname';      // first name  
$customer_lname = 'lastname';       // last name 
$passwordLength = 10;               // the lenght of autogenerated password
$passowrd       = '123456';         // you can assign password or auto generated password, you have two option

$customer = Mage::getModel('customer/customer');
$customer->setWebsiteId(Mage::app()->getWebsite()->getId());
$customer->loadByEmail($customer_email);
/*
* Check if the email exist on the system.
* If exist, it will not create a user account. 
*/

if(!$customer->getId()) {

   //setting data as email, firstname, lastname, and password 

  $customer->setEmail($customer_email); 
  $customer->setFirstname($customer_fname);
  $customer->setLastname($customer_lname);
  //$customer->setPassword($customer->generatePassword($passwordLength)); // you can use autogenerated password
  //or
  $customer->setPassword($password); //or can set your own password as you wish

}
try{
  //the save the data and send the new account email.
  $customer->save();
  $customer->setConfirmation(null);
  $customer->save(); 
  $customer->sendNewAccountEmail();
}

catch(Exception $ex){
echo $message = $ex->getMessage(); 
}
?>