select :start_date + r weekend_date
  from (select rownum - 1 r 
          from all_objects 
         where rownum <= (:end_date - :start_date + 1))
 where to_char(:start_date + r, 'Dy') in ('Sat', 'Sun');
 
:start_date := to_date('01/01/2002', 'mm/dd/yyyy');
:end_date := to_date('04/01/2002', 'mm/dd/yyyy');
 
01/05/2002
01/06/2002
01/12/2002
01/13/2002
01/19/2002
01/20/2002
01/26/2002
01/27/2002
02/02/2002
02/03/2002
02/09/2002
...
03/24/2002
03/30/2002
03/31/2002