This is great for people building websites for clients who want to have their own branding all over the installation.
function my_custom_login_logo() { echo '<style type="text/css"> h1 a { background-image:url('.get_bloginfo('template_directory').'/images/custom-login-logo.gif) !important; } </style>'; } add_action('login_head', 'my_custom_login_logo');