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.

Eric Mann

Gives you the option of adding a Javascript-powered fading image gallery as a sidebar widget. The widget pulls its images from previous posts and automatically re-sizes them for display in the appropriate area.

Rotating Image Widget

Create a jQuery-driven rotating image sidebar widget.

Theme Checklist vs Rotating Image Widget