gistfile1.php

<?php if ( ! have_posts() ) : ?>
	<p>We couldn't find any resources.</p>
<?php 
	endif; 
	$in_use = array();
?>
<ul class="resources">
<?php while ( have_posts() ) : the_post(); ?>
		
		<?php 
			$first_letter = substr(get_the_title(), 0, 1);
			if(in_array($first_letter, $in_use)):
		?>
				<li><a href="#"><?php the_title(); ?></a></li>
		<?php
			else:
			array_push($in_use, $first_letter);
		?>
			</ul>
			<h2><?php echo $first_letter; ?></h2>
			<ul class="resources">
				<li><a href="#"><?php the_title(); ?></a></li>
		<?php
			endif;
		?>
<?php endwhile; ?>
</ul>