Previously I wrote an article that detailed modifying the WordPress Most Commented plugin to display the most commented WordPress posts via the WP admin site. If you need more information on creating admin plugins or just wanted to glance over the article related to this one you can read it by clicking here. Something I did not include in that article was how to add code to the plugin that would also display a widget on the WP Admin dashboard. Below is basic information that should assist you in adding code that will display a dashboard widget.
I have been adding some additions to WordPress to lock it down a bit and keep regular users away from wp-admin. There is a bunch of stuff out there to do this type of thing but I found the best combination to upgrade your register/login system and to keep the average user away from wp-admin so they stay on the site was to use Register Plus and WP Block Admin. They both serve different purposes but combined together they provide a much nicer user experience.
Register Plus: This WordPress plugin will allow you to create custom emails to users, a custom registration form, a password strength meter, a captcha, user registration verification emails, and more. When creating the custom registration form you can add custom fields, add custom CSS, etc. All in all in provides complete customization of the registration form and process.
When I was initially attempting to do this it was because I did not want to display a majority of the WordPress pages I was creating in the navigation or in the Pages Widget. After some research I located information on the WordPress Codex about how to exclude certain pages however this was not going to work for me since I would constantly be having to modify the exclude list with hundreds more than if I could just include the pages I wanted to show in the navigation. Inside the [wp-root]/wp-includes/widgets.php file you can make a small modification followed by a change via the WordPress admin GUI.