9. A system for allowing a supplier of products or services to define a customized interface based on a particular set of products or services offered by the supplier, wherein the customized interface is extensible by other suppliers to accommodate similar products or services offered by the other suppliers, and wherein the extended customized interface is used by users to search for items of interest among the products or services offered by the suppliers, the system comprising: a processor; and a memory, the processor to: provide a first interface to a first supplier over a network, the first interface allowing the first supplier to define a customized second interface based on a particular set of products or services offered by the first supplier; receive from the first supplier (a) a product or service category and (b) a set of parameter definitions comprising parameter names and parameter data types, wherein the product or service category and the parameter definitions describe the particular set of products or services offered by the first supplier; create a new request type in a database based on the product or service category, and associating the set of parameter names and parameter data types with the new request type, wherein the customized second interface is based on the new request type; receive from the first supplier a first supplier link for sending product or service requests to the first supplier; associate the first supplier link with the newly created request type; and present the customized second interface to one or more other suppliers to allow them to extend the customized second interface by (c) adding further parameter definitions to further describe one or more other products or services offered by the one or more other suppliers in the same product or service category, and (d) adding one or more supplier links of the one or more other suppliers; thereby allowing a user to search the database for items of interest using the extended customized second interface, and allowing user requests for items of interest to be sent to the suppliers via the supplier links; and display the extended customized second interface to the user; send the user request to at least one of the other suppliers; and receive a response from the other suppliers, the response including data in the form of the customized second interface.
9. A system for allowing a supplier of products or services to define a customized interface based on a particular set of products or services offered by the supplier, wherein the customized interface is extensible by other suppliers to accommodate similar products or services offered by the other suppliers, and wherein the extended customized interface is used by users to search for items of interest among the products or services offered by the suppliers, the system comprising: a processor; and a memory, the processor to: provide a first interface to a first supplier over a network, the first interface allowing the first supplier to define a customized second interface based on a particular set of products or services offered by the first supplier; receive from the first supplier (a) a product or service category and (b) a set of parameter definitions comprising parameter names and parameter data types, wherein the product or service category and the parameter definitions describe the particular set of products or services offered by the first supplier; create a new request type in a database based on the product or service category, and associating the set of parameter names and parameter data types with the new request type, wherein the customized second interface is based on the new request type; receive from the first supplier a first supplier link for sending product or service requests to the first supplier; associate the first supplier link with the newly created request type; and present the customized second interface to one or more other suppliers to allow them to extend the customized second interface by (c) adding further parameter definitions to further describe one or more other products or services offered by the one or more other suppliers in the same product or service category, and (d) adding one or more supplier links of the one or more other suppliers; thereby allowing a user to search the database for items of interest using the extended customized second interface, and allowing user requests for items of interest to be sent to the suppliers via the supplier links; and display the extended customized second interface to the user; send the user request to at least one of the other suppliers; and receive a response from the other suppliers, the response including data in the form of the customized second interface. 10. The system of claim 9 , the processor further to display the extended customized second interface to the user.