Many web-developers have a very simple problem: "If a user returns to my web-site after it have been updated, he may not see the updates -- instead the cached copy on his computer."
There is a very simple workaround to this problem. Simply put this line:
<meta http-equiv="Refresh" content="72000">
within the <head> ... </head> element.
It will cause the browser to reload cached web pages older than 20 hours
I have tested the technique on the following browsers: Netscape Navigator