ThemesWP

Using Ultimate Custom ScrollBar for customize scrollbars, you get a very elegant and unique site. Consistent scroll behavior for every device. You can change scrollbar size, colors, animation, position from this settings page.
Plugin Features
<ul>
<li>Simple installation & activation</li>
<li>Supported touch devices.</li>
<li>Unlimited colors.</li>
<li>Lightweight.</li>
<li>Enable/Disable Option.</li>
<li>Easy Option Panel.</li>
<li>All browser supported</li>
</ul>
Free Options
<ul>
<li>Enable/Disable ScrollBar : You can enable or disable scrollbar using this option.</li>
<li>Cursor Width : You can increase or decrease cursor width using this option.</li>
<li>Rail Background Color : You can change rail background color from this color picker.</li>
<li>Cursor Color : You can change cursor color from this color picker.</li>
<li>Auto Hide Mode : You can select scrollbar auto hide mode from this selectbox.</li>
<li>Included all free options.</li>
<li>Cursor Border : You can control cursor border using this option.</li>
<li>Cursor Border Radius : You can control cursor border radius using this option.</li>
<li>Scroll Speed : You can control scroll speed using this option.</li>
<li>Mouse Scroll Step : You can control mouse scroll step using this option.</li>
<li>Emulate Touch : Enable cursor-drag scrolling like touch devices in desktop computer.</li>
<li>Minimum Cursor Height : You can set the minimum cursor height.</li>
<li>Bounce Scroll : Enable scroll bouncing at the end of content as mobile-like.</li>
<li>Horizrail Enabled : You can control horizontal scroll.</li>
<li>Rail Align : You can control alignment of vertical rail.</li>
<li>Rail Valign : You can control alignment of horizontal rail.</li>
<li>Enable Mousewheel : You can control Mousewheel using this option.</li>
<li>Enable Keyboard : You can enable or disable keyboard events using this option.</li>
<li>Hide Cursor Delay : You can set the delay in microseconds to fading out scrollbars.</li>
<li>Enable Scroll On Selection : You can enable auto-scrolling of content when selection text.</li>
<li>Cursor Drag Speed : You can set speed of selection when dragged with cursor.</li>
</ul>

Ultimate Custom ScrollBar

Using Ultimate Custom ScrollBar for customize scrollbars, you get a very elegant and unique site. Consistent scroll behavior for every device.

masumabdullah

<h3>Winsome nice scrollbar by http://abdullahmasum.elance.com/</h3>
This plugin will add a nice custom scrollbar. No shortcode needed and very lightweight.
Plugin Features
<ul>
<li>Unlimited color</li>
<li>Strong admin panel for customizing</li>
<li>Border and brder-radius supports </li>
<li>Mobile touch option. </li>
<li>Very Lightweight.</li>
<li>Controlling scroll speed 
& many More</li>
</ul>
Live Preview: http://www.mhost.5gbfree.com/demo

Winsome Nice Scrollbar

Great plugin

This plugin will add a nice custom scrollbar. You can controll scrollbar settings from admin nice scrollbar admin panel.

Ultimate Custom ScrollBar vs Winsome Nice Scrollbar