Add an invoice link to Event Espresso WP User Integration addon version 1.9.7 and below. This is will be added in the WP User Integration addon version 1.9.8 and was requested in this forum post: http://eventespresso.com/topic/add-an-invoice-link-to-the-my-events-page/#post-31994

my_events_page.php

<?php
if (!function_exists('event_espresso_my_events')) {
  function event_espresso_my_events(){
		global $espresso_premium; if ($espresso_premium != true) return;
		global $wpdb, $org_options;	
		global $ticketing_installed;
		//$wpdb->show_errors();
		require_once('user_vars.php');
		?>
		
		<div id="configure_organization_form" class="wrap meta-box-sortables ui-sortable">
		<div id="event_reg_theme" class="wrap">
		<div id="icon-options-event" class="icon32"></div><h2><?php echo _e('My Events Management', 'event_espresso') ?></h2>
		<div id="poststuff" class="metabox-holder">
	<?php
		if($_POST['cancel_registration']){
			if (is_array($_POST['checkbox'])){
				while(list($key,$value)=each($_POST['checkbox'])):
					$del_id=$key;
					//Delete discount data
					$sql = "DELETE FROM " . EVENTS_ATTENDEE_TABLE . " WHERE id='$del_id'";
					$wpdb->query($sql);
					
					$sql = "DELETE FROM " . EVENTS_MEMBER_REL_TABLE . " WHERE attendee_id='$del_id'";
					$wpdb->query($sql);
				endwhile;	
			}
			?>
		<div id="message" class="updated fade"><p><strong><?php _e('The event(s) have been successfully removed from your account.','event_espresso'); ?></strong></p></div>
	<?php
		}
	?>
	<form id="form1" name="form1" method="post" action="<?php echo $_SERVER["REQUEST_URI"]?>">
	<div style="clear:both; margin-bottom:30px;"></div>
	<table id="table" class="widefat my_events_table" width="100%"> 
		<thead>
			<tr>
			  <th class="manage-column column-cb check-column" id="cb" scope="col" style="width:5%;"></th>
			  <th class="manage-column column-title" id="name" scope="col" title="Click to Sort" style="width:10%;"><span><?php _e('Event Name','event_espresso'); ?></span><span class="sorting-indicator"></span></th>
			  <th class="manage-column column-title" id="event" scope="col" title="Click to Sort" style="width: 10%;">
				<span><?php _e('Type','event_espresso'); ?></span>
				<span class="sorting-indicator"></span>
			  </th>
			  <th class="manage-column column-author" id="start" scope="col" title="Click to Sort" style="width:10%;"><span><?php _e('Date','event_espresso'); ?></span><span class="sorting-indicator"></span></th>
			  <th class="manage-column column-date" id="begins" scope="col" title="Click to Sort" style="width:5%;"><span><?php _e('Time','event_espresso'); ?></span><span class="sorting-indicator"></span></th>
			  <th class="manage-column column-date" id="status" scope="col" title="Click to Sort" style="width:5%;"><span><?php _e('Status','event_espresso'); ?></span><span class="sorting-indicator"></span></th>
			  <th class="manage-column column-date" id="attendees" scope="col" title="Click to Sort" style="width:5%;"><span><?php _e('Cost','event_espresso'); ?></span><span class="sorting-indicator"></span></th>
			  <th class="manage-column column-date" id="invoice" scope="col" style="width:5%;"><?php _e('Invoice','event_espresso'); ?></th>
			  <?php echo $ticketing_installed == true?'<th class="manage-column column-author" id="ticket" scope="col" style="width:10%;">'.__('Ticket','event_espresso').'</th>':''; ?>
			</tr>
	</thead>
		<tbody>
	<?php 
			$wpdb->get_results("SELECT id FROM ". EVENTS_MEMBER_REL_TABLE . " WHERE user_id = '" . $current_user->ID . "'");
			if ($wpdb->num_rows > 0) {
				$events = $wpdb->get_results("SELECT e.id event_id, e.event_name, e.event_code, e.start_date, e.event_desc, e.display_desc, a.id attendee_id, a.event_time start_time, a.payment_status, a.payment_date, a.amount_pd, u.user_id user_id, a.registration_id, a.lname, a.lname, a.price_option, a.event_time
													FROM " . EVENTS_ATTENDEE_TABLE . " a
													JOIN " . EVENTS_MEMBER_REL_TABLE . " u ON u.attendee_id = a.id
													JOIN " . EVENTS_DETAIL_TABLE . " e ON e.id = u.event_id
													WHERE u.user_id = '" . $current_user->ID . "'");
				foreach ($events as $event){
						$event_id = $event->event_id;
						$event_code = $event->event_code;
						$attendee_id = $event->attendee_id;
						$registration_id = $event->registration_id;
						$lname = $attendee->lname;
						$fname = $attendee->fname;
						$event_name = $event->event_name;
						$start_date = $event->start_date;
						$start_time = $event->start_time;
						$event_desc = $event->event_desc;
						$display_desc = $event->display_desc;
						$payment_status = $event->payment_status;
						$amount_pd = espresso_attendee_price(array('attendee_id'=>$attendee_id));
						$payment_date = $event->payment_date;
						$ticket_type = $event->price_option;
						if ($payment_status == ''){
							$payment_link = get_option('siteurl') . "/?page_id=" . $org_options['return_url'] . "&id=" . $attendee_id;
							$payment_status = '<a href="' . $payment_link . '">Pay Now</a>';
						}
						$event_url = home_url() . "/?page_id=" . $org_options['event_page_id']. "&regevent_action=register&event_id=". $event_id;
						$event_link = '<a class="row-title" href="' . $event_url . '">' . stripslashes_deep($event->event_name) . '</a>';
						//Build the payment link
						$payment_url = home_url() . "/?page_id=" . $org_options['return_url'] . "&amp;registration_id=" . $registration_id;
						//$payment_link = '<a href="' . $payment_url . '" title="'.__('View Your Payment Details').'">' . event_espresso_paid_status_icon( $payment_status ) . '</a>';
						
						//Deprecated ticketing system support
						//If the custom ticket is available, load the template file
						if (file_exists(EVENT_ESPRESSO_UPLOAD_DIR . "/ticketing/template.php")){
							if (file_exists(EVENT_ESPRESSO_UPLOAD_DIR . "/ticketing/functions.php")){
								include_once(EVENT_ESPRESSO_UPLOAD_DIR . "/ticketing/functions.php");
								$qr_code = espresso_qr_code(array('attendee_id' => $attendee_id,'event_name' => stripslashes_deep($event_name), 'attendee_first' => $fname, 'attendee_last'=> $lname, 'registration_id'=> $registration_id, 'event_code'=> $event_code, 'ticket_type'=>$ticket_type, 'event_time'=>$event_time, 'amount_pd'=>$amount_pd));
							}
									//Build the ticket link
							$ticket_url = home_url() . "/?download_ticket=true&amp;id=" . $attendee_id . "&amp;registration_id=".$registration_id;
							$ticket_link = '<a href="' . $ticket_url . '">' . __('Download Ticket Now!') . '</a>';
						}
						
						//New ticketing system suport
						if (function_exists('espresso_ticket_launch')){
							$ticket_link = espresso_ticket_links($registration_id, $attendee_id);
						}
	
	?>
		<tr>
		<td><input name="checkbox[<?php echo $attendee_id?>]" type="checkbox"  title="Cancel registration for <?php echo $event_name?>"></td>
				  <td class="post-title page-title column-title"><strong><?php echo $event_link?></strong> </td>
				  <td class="post-title page-title column-title"><?php echo $ticket_type ?></td>
				  <td class="date column-date"><?php echo event_date_display($start_date)?></td>
				  <td class="date column-date"><?php echo $start_time?></td>
				  <td class="date column-date"><?php echo '<a target="_blank" href="' . $payment_url . '" title="'.__('View Your Payment Details').'">'; ?><?php event_espresso_paid_status_icon( $payment_status ) . '</a>'; ?></td>
				  <td class="date column-date"><?php echo $org_options[ 'currency_symbol' ] ?><?php echo $amount_pd?></td>
				  <td class="date column-date"><a href="<?php echo home_url();?>/?download_invoice=true&amp;admin=true&amp;registration_id=<?php echo $registration_id ?>" target="_blank"  title="<?php _e('Download Invoice', 'event_espresso'); ?>"><img src="<?php echo EVENT_ESPRESSO_PLUGINFULLURL ?>images/icons/page_white_acrobat.png" width="16" height="16" alt="<?php _e('Download Invoice', 'event_espresso'); ?>" /></a></td>
				  <?php echo $ticketing_installed == true?'<td class="post-title page-title column-title">'.$ticket_link.'</td>':''; ?>
				  </tr>
		<?php } 
			}
			?>
			  </tbody>
			  </table>
			  <div class="bottom_settings" style="clear:both; margin-bottom:30px;">
			<input type="checkbox" name="sAll" onclick="selectAll(this)" /> <strong><?php _e('Check All','event_espresso'); ?></strong> 
			<input name="cancel_registration" type="submit" class="button-secondary" id="cancel_registration" value="<?php _e('Cancel Registration','event_espresso'); ?>" style="margin-left:100px;" onclick="return confirmDelete();"> <a style="margin-left:20px" class="button-primary"  onclick="window.location='<?php echo admin_url(); ?>profile.php#event_espresso_profile'"><?php _e('Your Profile','event_espresso'); ?></a>
		</div>
			</form>
	   </div>
	</div>       
			 </div> 
	
	<script>
	jQuery(document).ready(function($) {						
			
		/* show the table data */
		var mytable = $('#table').dataTable( {
				"bStateSave": true,
				"sPaginationType": "full_numbers",
	
				"oLanguage": {	"sSearch": "<strong><?php _e('Live Search Filter', 'event_espresso'); ?>:</strong>",
								"sZeroRecords": "<?php _e('No Records Found!','event_espresso'); ?>" },
				"aoColumns": [
								{ "bSortable": false },
								 null,
								 null,
								 null,
								 null,
								 null,
								 null,
								 { "bSortable": false },
								<?php echo $ticketing_installed == true?'{ "bSortable": false }':'';?>
							]
	
		} );
		
	} );
	</script>	
	<?php
	}

}

//Create a shortcode to place on a page
function event_espresso_my_events_fview(){
	echo event_espresso_my_events();
	wp_enqueue_style('my_events_table', EVNT_MBR_PLUGINFULLURL . 'styles/my_events_table.css'); //My events table css
	wp_enqueue_script('dataTables', EVENT_ESPRESSO_PLUGINFULLURL . 'scripts/jquery.dataTables.min.js', array('jquery')); //Events core table script
	wp_enqueue_script('dataTablesColVis', EVENT_ESPRESSO_PLUGINFULLURL . 'scripts/jquery.ColVis.min.js', array('jquery')); //Events core table column hide/show script
	wp_register_script('event_espresso_js', (EVENT_ESPRESSO_PLUGINFULLURL . "scripts/event_espresso.js"), false);
	wp_enqueue_script('event_espresso_js');
	return;
}
add_shortcode('ESPRESSO_MY_EVENTS', 'event_espresso_my_events_fview');