<select>

<?php
$postlist = get_posts( array('posts_per_page'=>-1,'post_type'=>'page'));
foreach ($postlist as $page): ?>

<option value="<?php echo get_permalink($page->ID); ?>" <?php if (get_the_ID() == $page->ID){ echo 'selected="selected"'; } ?>><?php echo $page->post_title; ?></option>
<?php endforeach;
?>

</select>