Web service for testing client code response to error conditions and delays?

I am building an application that consumes several web services. I am trying to test this portion of the application. Specifically, I am trying to test how my code response to errors and delays from the web service.

I have seen a web service that lets you pass in a delay and/or an error code via URL parameters. It then responses with that error code after the designated delay. Unfortunately, I have lost that link. I have done numerous Google searches and have not been able to find it.

Does anyone know of a web service that can be called from a client and will generate designated error responses after designated delays?