$list_epoch = 1;$list = array( 'blah', 'yadda', 'etc');if(($_SERVER['HTTP_REFERER'] == 'http://georgebushisyournewbicycle.com/') && !($_COOKIE['annoy_spacehobo'])) { # SpaceHobo stares at you disapprovingly. # Do not offer him cookies again, and instead serve a random entry. $phrasen = array_rand($list); $phrase = $list[$phrasen];} else { # PHP session cookie junk session_name('annoy_spacehobo'); session_start(); # Just in case you need to invalidate everyone's list cache. # This also serves as array initialization for new visitors. if($_SESSION['list_epoch'] < $list_epoch) { $_SESSION['list_epoch'] = $list_epoch; $_SESSION['list_used'] = array(); } # If the user has gone through all phrases, reset. if(count($_SESSION['list_used']) >= count($list)) { $_SESSION['list_used'] = array(); } # Weed out entries the user has already seen. # NOTE: Figure out something more efficient if list ever gets # over a couple thousand. $list_candidates = array(); foreach($list as $a) { if(!in_array($a, $_SESSION['list_used'])) { $list_candidates[] = $a; } } if(count($list_candidates) > 0) { $phrasen = array_rand($list_candidates); $phrase = $list_candidates[$phrasen]; $_SESSION['list_used'][] = $phrase; } else { # The only reason $list_candidates should have zero entries is if # $list had duplicate entries. Just in case, reset and serve up # something random. $_SESSION['list_used'] = array(); $phrasen = array_rand($list); $phrase = $list[$phrasen]; }}