This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
Back in the beginning of servlets somebody created the Invoker servlet. With the invoker active you had the appearance of servlet classes in the default package being called without a web.xml entry. This was an illusion because the invoker was really getting the request first - as configured in web.xml.
This was supposed to make it easier for newcomers to experiment with servlets without getting into web.xml but it has proved to be a disaster and caused much more confusion than web.xml ever did.