BuddyPress.org

I’ve been using: https://wordpress.org/extend/plugins/dbd-login-style/

I haven’t been able to figure out the logo image and so I just overwrote this image: /wp-admin/images/logo-login.gif

I imagine with a different CSS you might be able to easily change it. If you figure that out, I’d love to hear since I hate core changes but was too lazy in this case.