Mario Peshev

Theme Mentor is a cousin of the Theme-Check plugin getting deeper into the code analysis.
It’s using different approaches to monitor for common problems regarding theme reviews from the WordPress Theme Reviewers Team. It is prone to fault analysis, so use only as a reference for improving your code base even further.
Currently supported validations:
<ul>
<li>Mark all tags in template files</li>
<li>Mark all tags in template files</li>
<li>Warn about query_posts() usage</li>
<li>capital_P_dangit control (disallow any WordPress spelling other than WordPress as is – that is WORDPRESS and WordPress, ugh)</li>
<li>wp_deregister_script(‘jquery’) is forbidden</li>
<li>wp_dequeue_script(‘jquery’) is forbidden</li>
<li>prevent global $data; call as a common troublemaker (props @pippinsplugins)</li>
</ul>
header.php specific
<ul>
<li>Make sure that wp_head is before </li>
<li>Ensure that wp_title(…) is called within and tags</li>
</ul>
footer.php specific
<ul>
<li>Make sure that wp_footer is before </li>
</ul>

Theme Mentor

Theme Mentor is a cousin of the Theme-Check plugin getting deeper into the code analysis.

Mike Bijon

Get better uploaded quality or save bandwidth: Change the JPEG compression-level of uploaded images and thumbnails.
‘Resized Image Quality’ lets you easily change the compression-level of uploaded JPEG images and thumbnails. Set it for maximum quality when you want images to look their best, or take advantage of lower quality settings to save bandwidth.
The only interface is a slider aqdded to the Settings > Media admin page, making this easier to use than other compression plugins or functions.php settings.

WP Resized Image Quality

Get better uploaded quality or save bandwidth: Change the JPEG compression-level of uploaded images and thumbnails.

Theme Mentor vs WP Resized Image Quality