This is really simple and interesting. But you need to know how to use Photoshop or any image editing tools before you can start customize it.
What we will doing here is we want to customize our WordPress login page images. By default, your WordPress login page looks like this.
To change it into something else, you must edit or replace this two image files, login-bkg-tile.gif and login-bkg-bottom.gif with your own unique custom design. This two files can be found from your wp-admin/images folder.
But if you want to design your own custom images, you must make sure that your image background colour must not in white or you will not see text on your login page.
Once you have finished editing or design your login page image, transfer them to your wp-admin/images folder. Now you can view your new customized login page at http://<your domain>/wp-login.php.
Here is mine.
Want to see a live preview? Just go to my login page. Cool huh? :d
Customize the WordPress login page [via rishiraj.info]