Heres a little tip on how to display a list of WordPress authors with avatars and username.

Instructions
Add this code anywhere in your 'templates' file.

<?php
     $display_admins = false;
     $order_by = 'post_count'; // 'nicename', 'email', 'url', 'registered', 'display_name', or 'post_count'
     $order = 'DESC';
     $role = ''; // 'subscriber', 'contributor', 'editor', 'author' - leave blank for 'all'
     $avatar_size = 161;
     $hide_empty = false; // hides authors with zero posts
		
     if(!empty($display_admins)) {
          $blogusers = get_users('orderby='.$order_by.'&role='.$role);
     } else {

     $admins = get_users('role=administrator');
     $exclude = array();
     
     foreach($admins as $ad) {
          $exclude[] = $ad->ID;
     }

     $exclude = implode(',', $exclude);
     $blogusers = get_users('exclude='.$exclude.'&orderby='.$order_by.'&order='.$order.'&role='.$role);
     }
	
     $authors = array();
     foreach ($blogusers as $bloguser) {
     $user = get_userdata($bloguser->ID);

     if(!empty($hide_empty)) {
          $numposts = count_user_posts($user->ID);
          if($numposts < 1) continue;
          }
          $authors[] = (array) $user;
     }
		
     echo '<ul id="grid-contributors">';
     foreach($authors as $author) {
          $display_name = $author['data']->display_name;
          $avatar = get_avatar($author['ID'], $avatar_size);
          $author_profile_url = get_author_posts_url($author['ID']);
			
          echo '<li class="single-item">';
          echo '<div class="author-gravatar"><a href="', $author_profile_url, '">', $avatar , '</a></div>';
          echo '<div class="author-name"><a href="', $author_profile_url, '" class="contributor-link">', $display_name, '</a></div>';
          echo '</li>';
          }
     echo '</ul>';
?>