I need an wordpress plugin that works on multi-site and creates a widget textbox that automatically runs in every blog of my network.

This should be possible:

1 - The widget should work exactly like the default "text widget" and should only be edited by super-admin. Basically it will hold ads, so it must accept HTML.
2 - Super-admin should edit its content by the Super-admin menu.
3 - Super-admin should choose if it will work in mainblog or not.
4 - There should be an option to turn it off without needing to deactivate the plugin.
4 - Admins in the network should be capable of changing the position of the widget as usual (this is just to prevent locking it in some specific position).

Thank you.