Common Page Footer
This allows all your web pages to have a common footer without the need of server-side includes which most ISPs don't support. This script displays a 'mail me' address, web site author contact and a 'last updated' date which is passed in via an argument.
Obviously you could do something similar to have a common header if you wanted.
Example
Every page on this web site uses this script!. Use your browser's 'View Source' command to view the page, the script is invoked at the end of the page.