1. A web site system capable of rescuing invalid URLs included in URL request messages, the system comprising: a data repository that stores supplemental product information for different products, the product relationship information including a product identifier for a first product and supplemental product information for the first product; and a web server system for a website in communication with the data repository, said web server system comprising one or more computing devices, wherein the web server system is responsive to at least some invalid URLs received from a user computing device by: identifying a first product identifier referenced in an invalid URL referencing content not found on the website, the invalid URL including a domain name of the web server system and the first product identifier, said first product identifier corresponding uniquely to a first product; determining the first product identifier from the invalid URL; obtaining from the data repository supplemental product information for the first product using the first product identifier; determining from the supplemental product information that the first product has been superseded by a second product, said second product being different than the first product; determining that the second product is offered on the website; and at least partly in response to determining the second product is offered, providing to the user computing device a page having content associated with the second product, the page having a second URL including a second product identifier and the domain name of the web server system.
1. A web site system capable of rescuing invalid URLs included in URL request messages, the system comprising: a data repository that stores supplemental product information for different products, the product relationship information including a product identifier for a first product and supplemental product information for the first product; and a web server system for a website in communication with the data repository, said web server system comprising one or more computing devices, wherein the web server system is responsive to at least some invalid URLs received from a user computing device by: identifying a first product identifier referenced in an invalid URL referencing content not found on the website, the invalid URL including a domain name of the web server system and the first product identifier, said first product identifier corresponding uniquely to a first product; determining the first product identifier from the invalid URL; obtaining from the data repository supplemental product information for the first product using the first product identifier; determining from the supplemental product information that the first product has been superseded by a second product, said second product being different than the first product; determining that the second product is offered on the website; and at least partly in response to determining the second product is offered, providing to the user computing device a page having content associated with the second product, the page having a second URL including a second product identifier and the domain name of the web server system. 2. The system of claim 1 , wherein providing to the user computing device the page comprises redirecting the user computing device to the page.