imdb=# select keyword, count(movie_id) as freq from keyword, movie_keyword WHERE keyword.id = movie_keyword.keyword_id GROUP BY keyword ORDER BY freq DESC LIMIT 20;
          keyword          | freq  
---------------------------+-------
 sex                       | 72496
 hardcore                  | 58448
 character-name-in-title   | 41840
 independent-film          | 34710
 based-on-novel            | 29440
 female-nudity             | 20522
 murder                    | 19528
 number-in-title           | 14364
 nudity                    | 14120
 based-on-play             | 13753
 love                      | 12645
 father-son-relationship   | 10799
 sequel                    | 10544
 death                     | 10307
 family-relationships      |  9942
 husband-wife-relationship |  9638
 police                    |  9234
 violence                  |  9226
 non-fiction               |  9060
 anal-sex                  |  8567
(20 rows)