== Simple == 

* Mark all <link> tags in template files
* Mark all <script> tags in template files
* Warn about query_posts() usage
* capital_P_dangit control (disallow any WordPress spelling other than WordPress as is - that is WORDPRESS and Wordpress, ugh)
* wp_deregister_script('jquery') is forbidden
* wp_dequeue_script('jquery') is forbidden
* prevent global $data; call as a common troublemaker (props @pippinsplugins)

== Complex ==

=== header.php ===

* Make sure that wp_head is before </head>
* Ensure that wp_title(...) is called within <title> and </title> tags

=== footer.php ===

* Make sure that wp_footer is before </body>