Lets you add a custom CSS class to each widget instance.
ZigWidgetClass adds a free text field to each widget control form on your widget admin page. Enter a CSS class name in the box and it will be added to the classes that WordPress applies to that widget instance.
It has been tested and verified to work with the Widget Logic plugin, the Widget Context plugin and now (November 2013) the WP Page Widget plugin. If you have problems getting it to work with one of those plugins, make sure you are using the latest version(s).
IMPORTANT: It only works with widgets created by extending the built-in multi-widget class! If it appears not to work on a certain widget, that widget is probably not a multi-widget.
Requires WordPress 3.5+ and PHP 5.2.4+.
For further information and support, please visit the ZigWidgetClass home page.