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.

itzoovim

WordPress Login Box (WPLB) lets you add a log in/out box to your website.
WPLB includes an options panel which gives you control over your form.
Features:
<ul>
<li>Different styles</li>
<li>Highly customizable</li>
<li>Lightweight</li>
<li>Can be integreated with any theme</li>
<li>Works well with other plugins</li>
<li>Hackable</li>
</ul>
This plugin lets you choose custom links for a forgot your password page,and registration page. 
It also lets you choose a url that you users will be redirected to after they log-in/out. 
You can also enable the option to not redirect your users to WP-Login after failed login attempts! 
This plugins works well with other member plugins, and can help you create an overall better user experience.
You can view a sample <a href="http://itzoovim.com/plugins/customize-and-add-a-wordpress-login-form-to-your-site/#sample_wordpres_login_form" rel="nofollow ugc">wordpress login form</a> by visiting this link.
<h3>Requirements</h3>
In order to work, WPLB needs the following :
<ol>
<li>PHP version 5+</li>
<li>Preferably the latest version of WordPress.</li>
</ol>
<h3>Donations</h3>
We are still working on a donations link at the moment. For now, leaving a nice rating will be appreciated as well.

WP Login Box

Easily add a forum like log in/out form to your site.

upPrev vs WP Login Box