HTML:
<META HTTP-EQUIV="Pragma" CONTENT="no-cache">
<META HTTP-EQUIV="Cache-Control" CONTENT="no-cache">
<META HTTP-EQUIV="expires" CONTENT="Wed, 26 Feb 1997 08:21:57 GMT">
<META HTTP-EQUIV="Expires" CONTENT="0">

PHP:
header("Expires: Mon, 26 Jul 1997 05:00:00 GMT");
header("Cache-Control: no-cache, must-revalidate");
header("Pragma: no-cache");

ASP:
Response.Expires = -1
Response.ExpiresAbsolute = Now() - 1
Response.cachecontrol = "no-cache"

JSP:
response.addHeader("Cache-Control", "no-cache");
response.addHeader("Expires", "Thu, 01 Jan 1970 00:00:01 GMT");