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.

Krzysztof Dryja (Aspexi)

Aspexi Easy Login URL:
<ul>
<li>changes your url/wp-login.php URL into your custom string i.e. url/login</li>
<li>changes your url/wp-login.php?action=register URL into your custom string i.e. url/register</li>
<li>changes your url/wp-login.php?action=lostpassword URL into your custom string i.e. url/forgot</li>
<li>related URLs fix (i.e. on login page) >=3.3.2</li>
<li>
backups original .htaccess file, restore option included
</li>
<li>
Not tested on multisite. Use at your own risk.
</li>
<li>Not tested on IIS7. Use at your own risk.</li>
<li>Be careful using this plugin with other which modify .htaccess file</li>
</ul>

Aspexi Easy Login URL

Aspexi Easy Login URL changes your url/wp-login.php URL into your custom string i.e. url/login and more (incl. Register and Forgot password links).

Login XChange vs Aspexi Easy Login URL