TechTarget has an article on how to set access control lists to define default file permissions. This came in handy for us, as we have several developers who work on our sites. The default file permissions would get annoying, as developer A would create some files which only he could edit, so developer B would have to use sudo to change the file permissions to a developers group.

With the TechTarget article, now all newly created files in our code directory are owned & editable by the developers group, making shared development much easier.