example results:
TranDate	TransactionAmount	Balance
2008-12-01 00:00:00.000	100.00	100.00
2008-12-02 00:00:00.000	0.00	100.00
2008-12-03 00:00:00.000	-60.00	40.00
2008-12-04 00:00:00.000	10.00	50.00
2008-12-05 00:00:00.000	0.00	50.00
2008-12-06 00:00:00.000	0.00	50.00

SET DATEFORMAT MDY
DROP TABLE #myBalances
CREATE TABLE #myBalances (
      [TranDate] DATETIME,
      [TransactionAmount] money,
      [Balance] money)
      
INSERT INTO #myBalances VALUES ('12/1/2008',100,100)
INSERT INTO #myBalances VALUES ('12/3/2008',-60,40)
INSERT INTO #myBalances VALUES ('12/4/2008',10,50)



DECLARE @StartDate DATETIME, @EndDate DATETIME
SET @StartDate = '12/1/2008'
SET @EndDate = '12/6/2008'

;with TallyCalendar as (
                       --5 years prior to today plus 5 years after
                       SELECT  dateadd( dd, -3650 + RW ,DATEADD(dd, DATEDIFF(dd,0,getdate()), 0)) As N
                       FROM (
                             SELECT TOP 7300 -- ~10 years of days
                               row_number() OVER (ORDER BY sc1.id) AS RW 
                             FROM Master.dbo.SysColumns sc1
                             CROSS JOIN Master.dbo.SysColumns sc2
                             ) X
                      )

SELECT DATEADD(DD, 0, Tally.n) AS TranDate, ISNULL(b.TransactionAmount, 0) AS TransactionAmount, x.Balance 
FROM TallyCalendar Tally 
LEFT JOIN #myBalances b ON b.TranDate = DATEADD(DD, 0, Tally.n)  
LEFT JOIN #myBalances x ON x.TranDate = (SELECT MAX(TranDate) AS TranDate FROM #myBalances WHERE TranDate <= DATEADD(DD, 0, Tally.n))
WHERE n BETWEEN DATEDIFF(DD, 0, @StartDate) AND DATEDIFF(DD, 0, @EndDate) 

USE tempdb;

DECLARE @Data
TABLE   (
        input_month     DATETIME NOT NULL,
        price           MONEY
        );

INSERT  @Data
VALUES  ('20090101', $50.00),
        ('20090201', $58.00),
        ('20090301', $65.00);
        
SELECT  Days.output_date,
        D.price
FROM    @Data D
CROSS
JOIN    (
        VALUES  (00), (01), (02), (03), (04), (05), (06), (07), (08), (09),
                (10), (11), (12), (13), (14), (15), (16), (17), (18), (19),
                (20), (21), (22), (23), (24), (25), (26), (27), (28), (29), (30)
        ) DayOffset (n)
CROSS
APPLY   (SELECT  DATEADD(DAY, DayOffset.n, D.input_month)) Days (output_date)
WHERE   MONTH(Days.output_date) = MONTH(D.input_month);

WITH Dates AS (
	SELECT
	 [Date] = CONVERT(DATETIME,'01/01/2010')
	UNION ALL SELECT
	 [Date] = DATEADD(DAY, 1, [Date])
	FROM
	 Dates
	WHERE
	 Date < '12/31/2010'
) SELECT
 [Date]
FROM
 Dates
OPTION (MAXRECURSION 400)