Widget Display Options adds fields to all registered widgets that allow you to contextually hide or show any widget based on a set of chosen conditions. Many of the conditions accept parameters so you could, for example, only show a widget on the single view of a given page or post, or hide it on the archive pages of a given post type or category, etc.
Additionally this plugin provides an input field to add custom classes to the widget wrappers.
Available Conditions:
Items marked with an * accept parameters.
For a complete description visit the online usage manual.