tgrk

Using Custom Logo you can replace WP default login/register page logo by placing URL to custom logo 
you have (in proper size of course ;)). It is done using JavaScript onload event. It is not ideal, because 
there is small delay. I will try to improve it as soon as possible(I created it because of need for one small 
project…). Reason for using approach is seamless WP upgrades without any need for backup wp-admin.css or 
changed wordpress-logo.png.

Custom Logo

Replace WordPress default login/register page logo with custom one.

joaomaridalho

A plugin that allows your brand, company, organization image to shine through your page.

SiteBrand Customizer

Simple, and it works! What else can I request!
Hope to see new features soon!

Congrats!

Works on spot!

Plugin that helps your wordpress installation look more customized includes a Page Loader and Custom Login Page using the same settings.

Custom Logo vs SiteBrand Customizer