Smarter Themes

pi Scrollbar wp is fully customizable wordpress scrollbar plugin.You can change scrollbar color, border radius, scroll speed, width, border style & other settings using plugin option page.
 Plugin Features
<ul>
<li>Simple installation & activation</li>
<li>Unlimited colors.</li>
<li>CSS3 animation.</li>
<li>Supported touch devices.</li>
<li>All browser supported</li>
<li>Custom Width.</li>
<li>Scrollbar border radius.</li>
<li>Scrollbar scroll speed.</li>
<li>Scrollbar border.</li>
<li>Auto Hide Enable/Disable Mode.</li>
<li>Lightweight Responsive.</li>
<li>Easy Option Panel.</li>
<li>Easy Documentation.</li>
</ul>

Scrollbar

Customize your browser scrollbars with unlimited styling and color using scrollbar wp plugin.

SoftHopper

WordPress custom scrollbar is highly customizable WordPress plugin. Features include vertical and/or horizontal scrollbar(s), adjustable scrolling momentum, mouse-wheel, keyboard and touch support, ready-to-use themes and customization via CSS, RTL direction and many more.
You can change almost 100+ demo style, ScrollBar scroll speed, Showing ScrollBar arrow button mode, ScrollBar auto hide mode, ScrollBar auto expand mode, ScrollBar moving mode by keyboard & other settings by using the options and shortcode of this plugin. 
<a href="http://wordpress-custom-scrollbar.softhopper.net/" rel="nofollow ugc">Click here</a> to see a live demo
Features include:
<ul>
<li>100+ scrollbar demo</li>
<li>Full page Scrollbar</li>
<li>Single Content Scrollbar</li>
<li>Custom Selector Scrollbar</li>
<li>Vertical and horizontal scrollbar support</li>
<li>Highly Customizable</li>
<li>Enable TinyMCE Button</li>
<li>ScrollBar scroll speed control</li>
<li>ScrollBar arrow button mode control</li>
<li>ScrollBar auto hide mode</li>
<li>ScrollBar auto expand mode</li>
<li>ScrollBar moving mode by keyboard</li>
<li>Shortcode Powered</li>
<li>Translation Ready</li>
<li>Responsive for all devices</li>
<li>All major browser supported</li>
<li>Easy to handle</li>
</ul>

Custom Content Scrollbar

WordPress custom scrollbar is highly customizable WordPress plugin.

Scrollbar vs Custom Content Scrollbar