This function turns an array into a nice list, separated with commas, with "and" before the final item.

nice_list.php

<?php

function nice_list($items) {
    if(count($items) == 1) return $items[0];
    if(count($items) == 2) return $items[0].' and '.$items[1];
    $last = array_pop($items);
    array_push($items, 'and '.$last);
    return implode(', ', $items);
}

$items[] = 'pebble';
$items[] = 'bean';
$items[] = 'peanut';
$items[] = 'marble';
$items[] = 'paperclip';

echo nice_list($items); // pebble, bean, peanut, marble, and paperclip

Check out this gist for a more advanced version of the function that supports custom string wrapping.