SELECT 1 Type, start Date from table
UNION ALL
SELECT -1, end from table

1 2013-03-01
 1 2013-05-01
 1 2013-06-01
-1 2013-07-10
-1 2013-07-31
-1 2013-08-30
 1 2013-09-15
 1 2013-10-01
-1 2013-11-30
-1 2013-12-31

SELECT a.Type, a.Date
     , (SELECT SUM(b.Type)
          FROM set1 b
         WHERE b.Date < a.Date
            OR (b.Date = a.Date AND b.Type <= a.Type)) RunningTotal
FROM set1 a

1 2013-03-01 1
 1 2013-05-01 2
 1 2013-06-01 3
-1 2013-07-10 2
-1 2013-07-31 1
-1 2013-08-30 0
 1 2013-09-15 1
 1 2013-10-01 2
-1 2013-11-30 1
-1 2013-12-31 0

SELECT a.Date Start
     , (SELECT MIN(b.Date)
          FROM set2 b
         WHERE Type = -1
           AND RunningTotal = 0
           AND b.Date > a.Date) End
  FROM set2 a
 WHERE Type = 1 AND RunningTotal = 1