Quick way to list images from Wordpress posts without using "attachment" ("media") posts. Just parse some fresh posts to list found <img/> tags.

wordpress-photo-digest

<?php
// fetch fresh published posts 
$imgPosts = get_posts(array(
	'posts_per_page'  => 10, // max count
	'orderby'         => 'post_modified',
	'order'           => 'DESC',
	'post_type'       => 'post',
	'post_status'     => 'publish' 
));

// collectin' parsed <img/> tags
$attaches = array();
foreach ($imgPosts as $p => $post) {
    // find first <img/> tag found in post body - or go to next post
	if(!preg_match('/<img .+(?=\/>)\/>/i', $post->post_content,$matches))
		continue;
	$attaches[]= $matches[0];
}
// garbagin' useless posts
unset($imgPosts);

// printing collected images
foreach ($attaches as $a => $attach) {
	print($attach); // <img src="[image url as written in post]" ... />
}
?>