Changed example.com to example.domain and renamed sites-available/example.com.conf to sites-available/example.domain.conf.
Changed example.com to example.domain.  Added new user-agent strings and referrers.  Added line for blocking of empty user-agent string which is NOT enabled by default.  Added additional comments.  See the new NOTE comments, particularly NOTE 3.
Changed example.com to example.domain.  Expanded the blacklist.conf section to reflect recent changes.