WordPress 2.5 has the ability to customize your administration dashboard with the help of widgets.
After poking around WordPress 2.5 codes, I have come out with this Dashboard Widget Sample Plugin. BUT do note that this plugin does not include Dashboard Widget Controls. If I have the time, I will add that in or perhaps I will create another plugin called “Dashboard Widget (With Controls) Sample Plugin”.
You can get/read the codes here: http://lesterchan.net/wordpress/2008/03/19/dashboard-widget-without-controls-sample-plugin/