Secure paths that may contain sensitive information.

This includes SSL certs, checks, etc.  Leaving these world readable is a 
serious security issue, since an exploit of any service on the system will
provide access to a great deal of privileged information.  The SSL certs are
obvious, but checks may include things like passwords for other services.

EDIT: Just realized, this is of significant importance to anyone with low-priv users on any of their systems, in addition to the exploit scenario.