Decomposing complex software systems into conceptually independent subsystems represents a significant software engineering activity that receives considerable research attention. Most of the research in this domain deals with the source code; trying to cluster together files which are conceptually related. In this paper we propose using a more informal source of information: file names. We present an experiment which shows that file naming convention is the best file clustering criteria for the software system we are studying.Based on the experiment results, we also sketch a method to build a conceptual browser on a software system.