There is a script called a frame buster script, cnn uses it. I've copied it below for you:
<script language="JavaScript" type="text/javascript">
<!-- Hide script from older browsers
setTimeout ("changePage()", 3000);
function changePage() {
if (self.parent.frames.length != 0)
self.parent.location=document.location;
}
// end hiding contents -->
</script>
Once this is placed between the head tags, any time someone tries to frame your site, it will take about 1.5 to 2 seconds and your site will bust out of the frame and open to a full browser window. The other thing that happens is it will be almost impossible for the user to use their back button to return to the site that had you framed as everytime they return to the frameset that had you framed, your site will bust out and open a full window (not a new window) the same window just with your site filling the entire screen.
Hope this helped!