A function to create a new WP member using the registration details provided for the event, this function also adds the event they have just registered onto into the my events database so the initial events is displayed within 'My Events'

espresso_create_wp_user.php

<?php
//* Please do NOT include the opening php tag, except of course if you're starting with a blank file

add_action('action_hook_espresso_save_attendee_data','espresso_create_wp_user', 10, 1);
function espresso_create_wp_user($attendee_data) {
    if( email_exists( $attendee_data['email'] ) == NULL ) {
		global $org_options;	
		
		// Generate the password and create the user
		$password = wp_generate_password( 12, false );
		$user_id = wp_create_user( $attendee_data['email'], $password, $attendee_data['email'] );
	
		// Set the users details
		//Additional fields can be found here: http://codex.wordpress.org/Function_Reference/wp_update_user
		wp_update_user(
			array(
				'ID'			=> $user_id,
				'nickname'		=> $attendee_data['fname'] . ' ' . $attendee_data['lname'],
				'display_name'	=> $attendee_data['fname'] . ' ' . $attendee_data['lname'],
				'first_name'	=> $attendee_data['fname'],
				'last_name'		=> $attendee_data['lname'],
				'description'	=> __('Registered via event registration form.', 'event_espresso'),
			)
		);
	
		// Set the role
		$user = new WP_User( $user_id );
		$user->set_role( 'subscriber' );
	
		// Email the user
		wp_mail( $attendee_data['email'], 'Welcome to ' . $org_options['organization'], 'Your Username: ' .$attendee_data['email']. ' Your Password: ' . $password );
		
		if ( function_exists('espresso_members_installed') && espresso_members_installed() == true ) {
			require_once(EVENT_ESPRESSO_MEMBERS_DIR . "member_functions.php"); //Load Members functions
			require(EVENT_ESPRESSO_MEMBERS_DIR . "user_vars.php"); //Load Members functions
			if ($user_id != 0) {
				event_espresso_add_user_to_event( $attendee_data['event_id'], $user_id, $attendee_data['attendee_id'] );
			}
		}
	
	} // end if

}