Greg - SiteOrigin

The Theme Checklist plugin is an unofficial tool to help developers get their theme ready for the WordPress.org theme directory. Install the plugin, then navigate to Tools > Theme Checklist to start checking.
We’ve compiled a some of the most common theme issues that we see in the theme review queue and put them on our site, <a href="http://themechecklist.org" rel="nofollow ugc">Theme Checklist</a>. This plugin simply loads in all the latest checks and gives you an easy interface to check off the issues as you check them in your own theme. Each issue has a detailed description with examples to help you avoid the them in your own theme.
Checks are dynamically loaded from the <a href="http://themechecklist.org" rel="nofollow ugc">Theme Checklist</a> website to ensure you’re always working with the latest version of the checks. If this fails, the plugin will fall back to the bundled checks in checks.json.

Theme Checklist

The Theme Checklist plugin is an unofficial tool to help developers get their theme ready for the WordPress.org theme directory.

Aaron D. Campbell

A widget that displays rotating images from a post’s gallery in the sidebar of 
your site. You just specify the post or page, and it will cycle through all the 
images from the gallery of that post or page. you can have as many of them as 
you want on your site simultaneously. Requires PHP5.
In WordPress 2.6, another plugin of mine has been included into the CORE to 
allow these to be reorder your images to make them display in whatever order you 
prefer. Until then, go get <a href="https://wordpress.org/extend/plugins/reorder-gallery/" rel="ugc">Reorder Gallery</a>!

Gallery Widget Pro

A widget that displays rotating images from a post's gallery in the sidebar of your site. Requires PHP5.

Theme Checklist vs Gallery Widget Pro