This plugin gives you a widget that displays a different Chinese character every day. The characters are randomly plucked from a list that includes all the commonly-used characters plus a few somewhat rare characters.
<h3>Uninstallation</h3>
<ol>
<li>Delete the hanzi-of-the-day folder from your site’s wp-content/plugins directory.</li>
<li>Delete the ($table_prefix)hanzi_of_the_day_ordinals table from your database.</li>
</ol>

Hanzi of the Day

A widget that displays a different Chinese character every day.

Techni Orchid LLC

Plugin Name: Sinosplice Tooltips 
Plugin URI: http://www.techniorchidllc.com/extras/wp/sinosplicetooltips/ 
Description: Easily add attractive tooltips to show the pinyin of Chinese characters, glosses for Japanese characters, or any use for tooltip text you can think of. Originally designed for and by Sinosplice.com. 
Version: 1.2.1 
Author: Andy Warmack 
Author URI: http://www.techniorchidllc.com/
Sinosplice Tooltips was conceived by John Pasden as a WordPress plugin 
replacement for the custom CSS and JavaScript code he had been using 
for years on Sinosplice.com. It was originally designed to provide 
pinyin readings for Chinese characters, but is flexible enough to be 
adapted to a variety of uses.

Sinosplice Tooltips

Create attractive and customizable tooltips showing the pinyin of Chinese characters, glosses for Japanese characters,…

Hanzi of the Day vs Sinosplice Tooltips