Adam Erstelle

This plugin allows a wordpress administrator to schedule a different theme to display on the website for holidays or special events for all visitors.
The theme will be overridden on the live site for all people who visit the site. Great for setting a Christmas theme!
If you just want to have a css file added instead of a whole theme, check out the wp-scheduled-styles plugin.

WP Scheduled Themes

Schedule a theme to display on the live site for holidays or special events. (Available from Appearance - Scheduled Themes)

WolfieZero

Ever wanted to show a particular section of cotent on a certain date but don’t want to do it to the whole post or page? “Display This When…” will allow you to block of a section of your content to only show on a set date.
Say if you want enter in an April Fools Day joke into your post, all you need do is this:
[displaythis when=”01-04″ format=”d-m”]Chinchillas know how to use dynamite![/displaythis]
And thus chinchillas will use dynamite on the 1st of April.
Default format type is “d-m-Y” (01-01-2011)

Display This When…

Display certain parts of content at a certain time

WP Scheduled Themes vs Display This When…