renp

A simple WordPress plugin which adds a “scroll to top” button to the bottom corner of the page if the page has been scrolled down. It is compatible with all major browsers and should work with all themes, including 
responsive and high resolution themes.
It is possible to configure the plugin in the admin area for choosing between light or dark colour schemes and size of the button as well.
If your theme doesn’t already contain this feature, you can simply add it by means of this plugin.

Scroll to Top Button

Displays a button in the bottom right corner for smooth scrolling to the top of the page.

andrewmatt

Create anchors and add up to to 30 scrolling animation effects to links that link to page anchors. You can set scroll speed and offset value.
<h4>Features</h4>
<ul>
<li>You can set scroll speed and offset value. </li>
<li>Choose from 30 Scrolling Animation Effects</li>
<li>You can exclude certain anchors from scrolling.</li>
<li>Works on all major browsers: IE, Firefox, Chrome, Safari…</li>
<li>Visual Editor Anchor Button</li>
<li>Shortcode Supported [anchor]anchorname[/anchor]</li>
</ul>
<h4>Video Tutorial</h4>

Easy Smooth Scroll Links

Create anchors and add up to to 30 scrolling animation effects to links that link to page anchors. You can set scroll speed and offset value.

Scroll to Top Button vs Easy Smooth Scroll Links