I recently started a web hosting business. I've gotten all the configuration figured out for paid users, but I'm having a problem for free users. I'd like to automatically place advertisements and a copyright notice at the bottom of every free user's page, but I don't know how to do this.
Obviously I could set it up so each new file contains a php include() of the file with my ad code in it, but the user could easily remove this.

Any ideas? I notice a lot of free hosts do this...

I apologize for double-posting, but I'm new here and couldn't find an edit button :$.
I just thought I should add what system I'm using in case that makes a difference.

> Apache2.2, PHP 5.2, Ubuntu 9.04 server, MySQL 5.

Since you're using apache, you should take a look at mod_layout or mod_substitute.

I've looked into the mod_layout a bit. Does anybody know of there's an up-to-date version of it? The only one I could find had documentation only for Apache2, which doesn't really apply to Apache2.2, since they revamped the module system...

You could use iads from the developers of ihost. The company has tutorials on how to install mod_layout. The company could install mod_layout and iads for free. Its only $40 one time for iads.