I’ve customized the WordPress login screen for several of my clients. It is a nice professional touch that goes a long way toward making a site feel like “home.” Today, I’ve released a plugin called Login Logo [install] that lets you easily do the same. There are other plugins that let you customize the login screen logo. But this one works with zero configuration. You just create the logo (PNG image with a transparent background), name it login-logo.png, and drop it into your /wp-content/ directory.
That’s it.

Here is an example modified login form
The plugin takes care of generating the correct CSS, based on the image’s size. For best results, use an image that is less than 326 pixels wide.

The source image that produced the above login screen
Install “Login Logo”
Click this link: Install the “Login Logo” plugin.
Alternatively, you can download it from the WordPress plugins directory.