Marcin Pietrzak

Display cool, animated fly-out or fade box with related content.
When a reader scrolls to the bottom of a single post, page, or custom post type, an animate box will be shown allowing the reader to select the previous or random available post or posts in the selected configuration:
<ol>
<li>Just previous</li>
<li>Previous in category</li>
<li>Previous in tag</li>
<li>Random</li>
<li>Related using YARPP (only post/pages)</li>
</ol>

upPrev

Great plugin. Works great, lightweight and doesn't take a lot of resources to manage. 

Great Plugin

Display cool, animated fly-out or fade box with related content.

Mario Aguiar

This plugin will add SexyLightBox to all the images in your blog, as long as they’re linking to the image file, it’s not necessary to add “rel=lightbox” anywhere, the plugin does it for you.

WP SexyLightBox

Plugin that integrates sexylightbox2 into wordpress.

upPrev vs WP SexyLightBox