Diana K. Cury

Very simple pluing, no configs, no screens, just action! 
Simple Smilies add all WordPress smillies in comments form and a simple javascript let users click them to insert. 
This is a very light plugin, the javascript only loads when in singular/single contexts, also there is no stylesheets.

Simple Smilies

Let users insert WordPress smilies when commenting in you site.

tompahoward

The Tiny Emotions plugin re-adds smilies and other emotion icons to the TinyMCE Rich Visual Editor 
The TinyMCE emotions plugin is normally bundled with TinyMCE, but it has be removed from the 
version within WordPress. This plugin puts it back in.
Most of the credit for this plugin belongs to [Moxiecode Systems] (http://tinymce.moxiecode.com/ ), 
who wrote the emotions plugin for TinyMCE, which this plugin uses.
<h3>Release Notes</h3>
<ul>
<li>0.0.1
<ul>
<li>Added workaround for TinyMCE compressor issues.</li>
</ul>
</li>
<li>0.0.0
<ul>
<li>Initial Release</li>
</ul>
</li>
</ul>

Tiny Emotions

The Tiny Emotions plugin re-adds smilies and other emotion icons to the TinyMCE Rich Visual Editor

Simple Smilies vs Tiny Emotions