Simply create a hash for today's date. Every time the script loads, check to see if the date of the server is the same date in the hash. If it is, produce a certain result. If it isn't, delete the original date and use the new date. Then produce a different result for that day.
"Age is nothing more than an inaccurate number bestowed upon us at birth as just another means for others to judge and classify us"
sulfericacid