Rating: 

- Bundle

- NetInfo (except for adding a printer)

- the different filesystem hierarchy:

- /private directory

- /Library

- /System

- the filesystem domains (local/networs and user)

- the boot process (rc.boot and rc Scripts)

- Startup items

- DirectoryServices

- the specific OS X processes

- nibindd

- netinfod

- ATSServer

- pbs

- Application packaging

- Frameworks

- HFS+

- Mac alias vs standard symbolic link

- Resource Fork for a file

- etc...

You can obtain the same information present in this book for free, take a look at these URLs:

http://wks.uts.ohio-state.edu/unix_course/unix_book.pdf

http://www.freebsd.org/projects/newbies.html