Sohelwpexpert

This plugin will enable tooltip in your WordPress theme.
Plugin Features
<ul>
<li>Very Lightweight.</li>
<li>Easy to use.</li>
<li>Customizable.</li>
</ul>

WP Tooltip

This plugin will enable tooltip in your Wordpress theme.

perfectpointmarketing

<h3>PPM Accordion by http://perfectpointmarketing.com</h3>
This plugin will enable tooltip in your WordPress theme.
Plugin Features
<ul>
<li>Very Lightweight. Only 10KB.</li>
<li>Easy to use.</li>
<li>Customizable. </li>
</ul>
Live Preview: http://perfectpointmarketing.com/plugins/ppm-tooltip

WP Tooltip vs PPM Tooltip