Hi Yoast,
I want to extend the WordPress SEO plugin to support some search engines in China, like Baidu, recently, but I fount the action hooks in WP SEO's plugin setting pages is very poor, often only one per setting page, so it made a little difficult to add extra field to some sections.
Here are some examples
First one, I wanted to add Baidu Webmaster Tool verification field on the dashboard page, I just found the wpseo_dashbord hook, but it's ok, the field to be added do is at the last of the page, so I just use this hook.
But, things change when I wanted to added baidu ping service on the wpseo_xml page, the only hook on this page is wpseo_xmlsitemaps_config, which is at the end of the page, but no hook is for the ping services options, so I think it would be handy if there is an action hook just below this section.
I do suggest you consider adding hooks when there maybe are other services providers.
best,
Andor