I know how to set up mod_rewrite to rewrite to a different page than the one accessed eg. RewriteRule mypage\.htm otherpage.htm
I don't know if this is possible, but instead of rewriting to a specific page can you rewrite to more than one page, either randomly selecting or possibley selecting an equal amount of times each page from a predefined list of pages?
Hey plan b, I'll give you a definite maybe to this question! :)
According to Apache, the format for a RewriteRule is:
RewriteRule Pattern Substitution so you cannot rewrite to a random "Substitution" target.
As you know, RewriteCond directives permit us to "massage" RewriteRules, making them conditional. I think you could create a condition (based on time of day perhaps) that would send visitors to different pages and it would appear to be a page selected at random.
The following rules will rewrite to file1.html if the current time is 0 to 29 seconds into the current minute, and to file2.html otherwise. If the first pattern matches, then we rewrite to file1 and stop rewriterule processing because of the [L] flag. Otherwise, the code falls through to the second rule, and we rewrite to file2.html and stop rewriterule processing.