WPMS Global Content is a plugin by n33rav that allows wordpress multisite network admin to set common header and footer content. These header and footer will be displayed in all child blogs. Its very usefull for displaying branding, advertisement and copyright message on all child blogs.
Admin can set content via familiar tiny mce editor or can paste html content.
Admin can provide comma separated list of blog ids to exclude from common header and footer.
This plugin has 3 options:
Exclude Following Blogs : Add a list of comma separated blog ids on which you don’t want to show global header/footer, plugin won’t add global header/footer to that blogs.
Header Content : Add content you want to display in header.
Footer Content : Add content you want to display in footer.
Plugin homepage: http://www.vareen.co.cc/documentation/wpms-global-content/