A smarter text widget that can be used to display table of contents in the sidebar.
When you use a shortcode in a text widget to dynamically create its content, the shortcode may yield empty content in some contexts, leaving you with an ugly looking empty widget in your sidebar with nothing more than a title and a blank rectange.
What you want is a text widget that will only show up when it does have content. This is such a widget.
Check out the plug-in homepage for in-depth information about the plug-in.