Chameleon CSS let your WordPress site to automatically select CSS file upon your specific condition, for current release Time, Date, Day and Month conditions are available. Generate CSS switch list (widget and template tag) Feature: Date, Time, Day and Month condition Date-Time souce: Client or Server CSS switch list (Widget and Template Tag) Very friendly UI Compatible with WP Super Cache Relate Link: Plugin Homepage & Document Credit Justin Tadlock : widget creating guide http://justintadlock.com/archives/2009/05/26/the-complete-guide-to-creating-widgets-in-wordpress-28 Jim Wurster : CSS switch list (feature suggest)