@felgallApr 29.2007 — #You can use JavaScript to set a cookie on their computer and provided they allow it to be set and don't delete it you can then stop them accessing the site again. Anything more secure requires server side processing.
@Tweak4Apr 30.2007 — #Of course, that could easily be foiled by the user either deleting or disabling cookies or disabling JavaScript. Is this going to be a "they absolutely can not visit more than once per day or my world will end" mission-critical situation, or a "I would really like it if they wouldn't visit more than once per day" situation?