I think it would be a neat idea if we could define what pages we want a specific widget on.
For instance. You have three pages.. About Us, Our Products, and News.
You have text widgets for photos of the CEO, a Photo of the Product, and an RSS feed widget for the latest news. You don't want them all to show up on every page.
When configuring the RSS widget, for example, perhaps there could be an option like  Enable this widget on ONLY the following pages - and you could select, or multiple-select, the pages that are appropriate for that widget. The default would be [X] Enable this widget on all pages.
I think this would be very useful in adding more freedom to the theme system. My guess is that it would not be 'easy' to implement, but would anyone like to share their feedback regarding the usefulness of being able to individually cherry-pick certain widgets for certain pages?