This 5 year article from 2007 (which was an update for the 2002 version) is still very up to date in 2012: Top Ten Mac OS X Tips for Unix Geeks – O’Reilly Media.
Originally it was to promote Mac OS X for Unix Geeks – O’Reilly Media. In between the updates there was Mac OS X Panther for Unix Geeks, 2nd Edition – O’Reilly Media.
Now it is to promote Mac OS X for Unix Geeks (Leopard), 4th Edition – O’Reilly Media.
Note there is also a nice, but independent presentation with the same title from HTGR-MacOSX.
–jeroen