I see what you are talking about.... What you could do is either using php, or javascript... You can either set a numbered variable in a session, or a cookie... Or even have a random number generated each time the page is loaded, and then use a switch statement to switch between titles... For instance with php(this would have to be ran wile the script is still in the header before you open the body tags):
$TInt = rand(1, 8);
switch($Tint) {
case 1:
echo "<title>Hello</title>";
break;
....
default:
echo "<title>Have a nice day</title>";
break;
}
Now with javascript you can either set a random number, also if I remember correctly you do not need to set this one in the headers of the script, also seeing as Javascript is action script, you could also create a loop that waits for a certain amount of seconds changes the number and switches for the result (not sure what the function for that would be though)...
var TInt = rand(); //or any other method
switch(TInt) {
case 1:
document.title('Hello'); //It might be a different name for the document object to write to the title...
break;
}