Thomas Schulte

This plugin dynamically shows preview screenshots of hyperlinks as tooltips on your WordPress site.
For the tooltip effect a jQuery plugin called “qTip2” is used internally. 
Find more about this great project here: http://qtip2.com/ 
The thumbnails are provided by http://thumbsniper.com and its API.

ThumbSniper

This plugin dynamically shows preview screenshots of hyperlinks as tooltips on your WordPress site.

Pigi

Using this small plugin you’ll be able to change:
<ul>
<li>Wp-admin </li>
<li>Wp-login</li>
<li>register</li>
</ul>
Logo
You need to insert your custom logo URL and Enable the Function
In the “0.5” Version you will also able to change the Default “Wp-admin” Link (to wordpress.org) with your Own Home Page Link, simply 
setting the custom url from the dropdown menu.
Edit Your Wp-login background
You do not need to do any other change.
<ul>
<li>Insert Your Blog’s Review for Free into <a href="http://blogadvice.org/submit-your-blog/" rel="nofollow ugc">BlogAdvice.org</a>; No registration Needed</li>
</ul>

Login Logo Customization

Change Your Wp-Admin, wp-login Logo, Custom Link And BACKGROUND

ThumbSniper vs Login Logo Customization