You know, the one typically at yoursite.com/wp-login.php. These are things you would put in the active theme's functions.php file.
Change the Logo
Is the WordPress logo by default, this changes the file path of that image. Change file path and file name to your own needs.
function custom_login_logo() {
echo '<style type="text/css">h1 a { background: url('.get_bloginfo('template_directory').'http://cdn.css-tricks.com/images/logo-login.gif) 50% 50% no-repeat !important; }</style>';
}
add_action('login_head', 'custom_login_logo');
Change the URL
... of where clicking that logo goes. By default it goes to WordPress.org, this will change it to your own homepage.
function change_wp_login_url() {
return bloginfo('url');
}
add_filter('login_headerurl', 'change_wp_login_url');
Change the Title
That is, change the title attribute of the image you just replaced. This changes it to the name of your blog in the settings.
function change_wp_login_title() {
return get_option('blogname');
}
add_filter('login_headertitle', 'change_wp_login_title');