This plugin gives you an easy way to customize your WordPress administrator dashboard. Simply select which admin widgets you'd like to show and for which user roles. You also get the option to add a new admin widget: just give it a title and enter your content into the WYSIWYG editor.

MiwoWidgets is a Widget Visibility Manager that allows to control which widgets will appear on which pages of your site.

Make a sidebar and place it anywhere in post or page with shortcode.