Did you ever wonder what exactly should be in the /usr/bin directory? Or maybe what goes inside the /usr/local/sbin directory? I found a great resource of the standards for UNIX describing all the directories in a basic UNIX filesystem. Very handy!
Filesystem Hierarchy StandardYou can find the document here: http://www.pathname.com/fhs/
The filesystem standard has been designed to be used by Unix distribution developers, package developers, and system implementors. However, it is primarily intended to be a reference and is not a tutorial on how to manage a Unix filesystem or directory hierarchy.
Mac OS X Hints
http://hints.macworld.com/article.php?story=2004031517034568