Nothing for you here - I'm just putting up some code here in public until I can get it hosted on wordpress.org
Widget Logic very first version.
[From the readme.txt]
Make all sidebar widgets conditional. Widget Logic lets you add wp 'conditional tags' logic to all registered widgets - eg "is_home()" or "is_category(5) || is_single()" - all from the usual widget admin interface.
== Description ==
This plugin gives every widget (even widget's lacking controls) an extra control called "Widget logic".
This text field allows you to specify any wp conditional tags logic to set when the widget appears. Use any standard Conditional Tags (
http://codex.wordpress.org/Conditional_Tags) and even combine them.
== Installation ==
1. Upload `widget-logic.php` to the `/wp-content/plugins/` directory
2. Activate the plugin through the 'Plugins' menu in WordPress
3. That's it. All the configuring is in the usual widget admin interface.