Traffic Splitter/Redirector...

I need a little program that will allow me to give it several URLS and do split tests/redirect traffic with them. For example... i'd like to submit lets say 4 different urls to the program. The program would then generate a URL and when somebody went to that generated URL, they would be forwarded to any of the 4 different urls that i submitted to the program. The program should split the traffic randomly but evenly accross all 4 urls. Users should be tracked with cookies and IP's... because if the program sent person A to url #1, the next time they come back to the site or click on the link they should be sent to the SAME url they were sent to originaly. Pretty simple script... i want it to be PHP based... that way it's quick... but remember it's very important that the user see the same page they clicked or were sent to before. even if they come back several weeks later. ## Deliverables 1) Complete and fully-functional working program(s) in executable form as well as complete source code of all work done. 2) Deliverables must be in ready-to-run condition, as follows (depending on the nature of the deliverables): a) For web sites or other server-side deliverables intended to only ever exist in one place in the Buyer's environment--Deliverables must be installed by the Seller in ready-to-run condition in the Buyer's environment. b) For all others including desktop software or software the buyer intends to distribute: A software installation package that will install the software in ready-to-run condition on the platform(s) specified in this bid request. 3) All deliverables will be considered "work made for hire" under U.S. Copyright law. Buyer will receive exclusive and complete copyrights to all work purchased. (No GPL, GNU, 3rd party components, etc. unless all copyright ramifications are explained AND AGREED TO by the buyer on the site per the coder's Seller Legal Agreement). ## Platform UNIX, PHP, mysql?