I want to give out some free hosting accounts and I want to know how to make it so banners are automatially placed on the top of each page. Anyone know how to do this?

You will need a script - cgi does the best job. Look at hotscripts (http://hotscripts.com) under virtual communities (http://www.hotscripts.com/Perl/Scripts_and_Programs/Virtual_Communities) and also the cgiresourceindex.com (http://cgi.resourceindex.com/Programs_and_Scripts/Perl/Homepage_Communities/).

Try a banner management program. Do a search on google if nobody has specific recommendations.

Ive never used this one but Ive heard good things about phpAds
here is an article that might be useful to you.
http://www.sitepoint.com/article/760

Misread :D Thought he meant normal rotating banner ads.

Hmm, that program won't put a banner on a page automatically. And the only way you can stop anyone from removing it is to take away their access to the opening and closing BODY tags and that requires a more involved script.

There is an Apache module called mod_layout you can use. Then you just add a few lines to their virtual host which will place your header/footer on every single one of their pages.

http://software.tangent.org/projects.pl?view=mod_layout

isn't there auto_prepend / append you can put in .htaccess?