One design pattern in Apache Sling (and Adobe Experience Manager) calls for making servlets based on resource types and not paths. See AEM Design Pattern: Base Servlets on Resource Types and A Brief Summary of Servlets in Apache Sling for more information about this.
Well then, how do you base a servlet on resource type vs. path? At Stackoverflow, a user asked this question and got the answer from Sharath Madappa. The @Slingservlet annotation use is described in the Sling documentation, Servlets and Scripts. The Adobe blog, Adobe@Adobe, documents the how to configure Sling servlets as well: CQ Tips and Tricks #1 – How to define a SlingServlet.
Update 23 April 2015
See Adobe CQ Help | Binding Adobe Experience Manager Servlets to ResourceTypes