Here we create a separate page with upcoming birthdays of site users.
Objective
Implementation - Server Side (PHP)
birthdays/init.php
// class that contains all data and functionality to add new type of members listing  
        class BIRTHDAYS_UsersPageData implements BASE_CLASS_IusersPageData
        {
            //set menu item for "Birthdays" page
            public function getMenuItem()
            {
                //$language - helps our site to be multilingual
                $language = OW::getLanguage();
                //initializing menu item
                $item = new BASE_MenuItem();
                $item->setLabel($language->text('base', 'user_list_menu_item_birthdays'))
                    ->setKey('birthdays')
                    ->setUrl(OW::getRouter()
                        ->urlForRoute('birthdays_users'))
                    ->setOrder(5)
                    ->setIconClass('ow_ic_calendar');
                if ( $this->isCase() )
                {
                    $item->setActive(true); // activate menu if "Birthdays" selected
                }
                return $item;
            }
            // check if URL is belong to "Birthdays" page
            public function isCase()
            {
                return false !== strstr(OW::getRequest()->getRequestUri(), OW::getRouter()->uriForRoute('birthdays_users'));
            }
            // "Birthdays" page's unique key
            public function getCase()
            {
                return 'birthdays';
            }
            // get data for "Birthdays" user listing
            public function getData( $first, $count )
            {
                $service = BOL_UserService::getInstance();
                //set date bounds for birthdays
                $period = array(
                    'start' => date('Y-m-d'),
                    'end' => date('Y-m-d', strtotime('+7 day'))
                );
                return array(
                    $service->findListByBirthdayPeriod($period['start'], $period['end'], $first, $count), // get users
                    $service->countByBirthdayPeriod($start, $end) // count users
                );
            }
        }
        // register data for "Birthdays" page. 
        OW::getRegistry()->addToArray('users_page_data', new BIRTHDAYS_UsersPageData());