Philip John

WordPress v3.3 removed the header from the admin interface, merging it with the admin bar.
This meant that the link to your site’s front page was taken away and you now have to go through drop down menus to get to the link.
Instead, this plugin puts that link back onto your admin interface.

Restore Admin Header

Add the link to your site back to the top of your WordPress admin!

Philipp15b

This plugin allows you to add your code/text to the headers and footers on all the blogs in the blog network and in the backend of all blogs too.
In addition, it is possible to replace the footer bar text in the backend completely.
You can access the settings under Network Admin -> Settings.

Sitewide (Admin) Header/Footer

Change the header/footer of the front- and backend of WordPress Multisite

Restore Admin Header vs Sitewide (Admin) Header/Footer