Get lists of all the keys stored in memcache server....

<?php
/**
 * Function to get all memcache keys
 * @author Manish Patel
 * @Created:  28-May-2010  
 */
function getMemcacheKeys() {

    $memcache = new Memcache;
    $memcache->connect('127.0.0.1', 11211) or die ("Could not connect to memcache server");

    $list = array();
    $allSlabs = $memcache->getExtendedStats('slabs');
    $items = $memcache->getExtendedStats('items');
    foreach($allSlabs as $server => $slabs) {
        foreach($slabs AS $slabId => $slabMeta) {
           $cdump = $memcache->getExtendedStats('cachedump',(int)$slabId);
            foreach($cdump AS $keys => $arrVal) {
                foreach($arrVal AS $k => $v) {                    
                    echo $k .'<br>';
                }
           }
        }
    }    
}//EO getMemcacheKeys()
?>

Hope it helps....