Vast HTML

This is a full featured plugin to help you edit your login just the way you want it. Lets you use or block the original wordpress 
css (the first plugin to do this). Comes with one pre made style you can use or deactivate. 
Very easy to create your own style using the style tags givin in the plugin. 
Please visit http://vasthtml.com/js/login-xchange-plugin/ for usage instructions.

Login XChange

This plugin will let you change the css of your login and register pages.

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.

Login XChange vs WP Login Box