drop table t;
create table t (date1 date, date2 date, val integer);
insert into t values(to_date('5/1/2007','MM/DD/YYYY'),
                     to_date('5/15/2007','MM/DD/YYYY'),
                     42);
insert into t values(to_date('5/16/2007','MM/DD/YYYY'),
                     to_date('6/15/2007','MM/DD/YYYY'), 
                     43);
commit;
alter session set nls_date_format='MM/DD/YYYY' nls_date_language=american;
SQL> select * from t;
DATE1      DATE2             VAL
---------- ---------- ----------
05/01/2007 05/15/2007         42
05/16/2007 06/15/2007         43

2 rows selected.

SQL> with 
  2    weeks as (
  3      select mindate+7*(rownum-1) begwk,
  4             mindate+7*(rownum-1)+6 endwk
  5      from (select next_day(min(date1)-6,'SATURDAY') mindate,
  6                   next_day(max(date2)+6,'FRIDAY') maxdate from t)
  7      connect by level <= trunc((maxdate-mindate)/7)
  8    )
  9  select greatest(nvl(date1, date '0001-01-01'),begwk) "From",
 10         least(nvl(date2, date '9999-12-31'),endwk) "To",
 11         val "Val"
 12  from t partition by (date1,val)
 13       right outer join weeks w
 14       on ( 1 = 1 )
 15   where w.begwk >= t.date1-6 and w.endwk <= t.date2+6
 16  /
From       To                Val
---------- ---------- ----------
05/01/2007 05/04/2007         42
05/05/2007 05/11/2007         42
05/12/2007 05/15/2007         42
05/16/2007 05/18/2007         43
05/19/2007 05/25/2007         43
05/26/2007 06/01/2007         43
06/02/2007 06/08/2007         43
06/09/2007 06/15/2007         43

8 rows selected.