This plugin gives every widget an extra control field called “Widget logic” that lets you control the pages that the widget will appear on.
The text field embedded into your widgets lets you use WP’s Conditional Tags, or any general PHP code.
There is also an option to add a WordPress ‘widget_content’ filter – this lets you tweak any widget’s HTML to suit your theme without editing plugins and core code.
This latest release – 0.52 – of Widget Logic, now has the option to import and export options which are saved to a text file containing all of the conditional logic.
There is an additional enhancement allowing you to select when the logic code runs. Check the plugin page for more details.