If you ever wondered why you don't have Intellisense support in Visual Studio 2005 when working on a Windows Communication Foundation (WCF) Service Configuration in a web project then here comes the workaround.
The reason for that is that you add your service configuration to the web configuration of the web application. Therefore when the project is initially generated the project template wizard also genrates a Web.config file and adds a namespace to the root-configuration element.
This namespace however prevents Intellisense from working correctly. Interesting that it also blocks the standard web configuration Intellisense supports. But since the xmlns attribute is not mandantory for the configuration element you can easily comment it out for the time working on the configuration. Without the namespace URI you have full Intellisense support for your service configuration like shown in the before - after screenshots below.