Global Header/Admin Bar

I have searched the forums for support of a global header (one that can be customized). The threads that I did come across don't seem to work with 3.0 as they were all plugins created for WPMU. I tried the older version (made for WPMU) but they do not work on 3.0.

I know there is a global footer plugin, but I can't for the life of me understand why one can't be made for the header. Am I missing something? Can anyone here point me to a solution that will provide custom global admin bars/ headers to all sites with a 3.0 install?

Thanks in advance.