likeagency

This plugin allows you to add a widget with custom text, link and a FontAwesome icon. In order for this plugin to work, please make sure you already use FontAwesome toolkit in your theme.
List of features:
<ul>
<li>Choose FontAwesome icon as an image for the button.</li>
<li>Add your own text and title for the widget.</li>
<li>Select header tag for the title.</li>
<li>Customize your FontAwesome image (position, color and background color).</li>
<li>Add custom URL to use the widget as a link.</li>
<li>Add extra button displayed below, with your own text.</li>
<li>The widget has its own stylesheet included, however with just necessary CSS to be displayed properly, so it doesn’t override the style for any theme you currently use. </li>
<li>You can also add your own CSS for this plugin via its Settings page.</li>
</ul>

Button with FontAwesome icons by LIKE.agency

This plugin allows to add a widget with custom text, link and a FontAwesome icon.

uepselon

This plugin offers your blog visitors a <a href="http://www.foxload.com/firefox-download/" title="firefox download" rel="nofollow ugc">firefox download</a> button in different formats and colors on the sidebar.
Different banner formats and colors are included. The plugin use the wordpress locale settings for proper language versions of firefox.
You can place firefox buttons as widget and if your theme does not support widgets, you can place this <code><?php if(function_exists('get_foxload_button'))get_foxload_button(); ?></code> php code at the preferred position in your template.

Foxload Firefox Download

Offers your blog visitors a firefox download button in different formats and colors on the sidebar.

Button with FontAwesome icons by LIKE.agency vs Foxload Firefox Download