Get Days from the given start date and end date

using a tally table (starting at n =1)

 SET dateformat MDY
 
 declare @startdate datetime,@enddate datetime 
 set @startdate='01/01/2010' 
 set @enddate='01/31/2010'
 
 SELECT @startdate + (n-1)
 FROM dbo.tally
 WHERE 
     n-1  < DATEDIFF (dd, @startdate, @enddate)

More on Tally tables here

Or if you don't want to use a 'physical' tally table, utilise a cte-based one

 SET dateformat MDY
 
 declare @startdate datetime,@enddate datetime 
 set @startdate='01/01/2010' 
 set @enddate='01/31/2010'
     
 ;WITH Nbrs_4( n ) AS ( SELECT 1 UNION SELECT 0 ),
       Nbrs_3( n ) AS ( SELECT 1 FROM Nbrs_4 n1 CROSS JOIN Nbrs_4 n2 ),
       Nbrs_2( n ) AS ( SELECT 1 FROM Nbrs_3 n1 CROSS JOIN Nbrs_3 n2 ),
       Nbrs_1( n ) AS ( SELECT 1 FROM Nbrs_2 n1 CROSS JOIN Nbrs_2 n2 ),
       Nbrs_0( n ) AS ( SELECT 1 FROM Nbrs_1 n1 CROSS JOIN Nbrs_1 n2 ),
       Nbrs  ( n ) AS ( SELECT 1 FROM Nbrs_0 n1 CROSS JOIN Nbrs_0 n2 )
 
 SELECT @startdate + (n-1)
 FROM (SELECT row_number() OVER(ORDER BY n) FROM Nbrs) Tally (n)
 WHERE
     n < DATEDIFF (dd, @startdate, @enddate) + 1

I wanted to add this as a comment to Kev's answer but it was too big. This is the fastest function to create a "virtual" tally table i have ever seen. You can step forward or backward and you can step more than one step at a time. (like when you want each monday in the given range)

 CREATE FUNCTION [DBO].[fnNumsTable](
      @pStartValue BIGINT= 1,
      @pEndValue        BIGINT= 1000000,
      @pIncrement    BIGINT= 1 
  )
  RETURNS TABLE
  AS
  -- +----------------------------------------------------------------------------------------------------------------
  -- ! O b j e c t         : [DWH].[fnNumsTable]
  -- ! R e t u r n s       : A table with number from startvalue to end value
  -- ! P a r a m e t e r s : Name                    DataType       Description
  -- +                       ======================= ============== ==================================================
  -- !                                                @pStartValue                        BIGINT= 1,
  -- !                                                @pEndValue                            BIGINT= 1000000,
  -- !                                                @pIncrement                            BIGINT= 1 
   -- + ---------------------------------------------------------------------------------------------------------------
   -- ! O b j e c t i v e   : Return a list of all numbers between startvalue to end value
   -- !                                             The table may be used to avoid cursors, generate a list of dates etc. 
   -- + ---------------------------------------------------------------------------------------------------------------
   -- ! H i s t o r y       :
   -- + ---------------------------------------------------------------------------------------------------------------
   -- !                       Date       Who   What
   -- +                       ========== ===== ========================================================================
   -- !                         2009-09-21 HAWI
   -- +----------------------------------------------------------------------------------------------------------------
     --Select n from dbo.[fnNumsTable](1000,2000,1) 
     --Select DATEADD(D,N,GETDATE()) from dbo.[fnNumsTable](1,365,7) 
  RETURN(
      WITH BaseNum (
          N 
      ) AS (
      SELECT 1 UNION ALL
      SELECT 1 UNION ALL
      SELECT 1 UNION ALL
      SELECT 1 UNION ALL
      SELECT 1 UNION ALL
      SELECT 1 UNION ALL
      SELECT 1 UNION ALL
      SELECT 1 UNION ALL
      SELECT 1 UNION ALL
      SELECT 1 
      ),
      L1 (
          N 
      ) AS (
      SELECT
          bn1.N 
      FROM
          BaseNum bn1 
          CROSS JOIN BaseNum bn2 
      ),
      L2 (
          N 
      ) AS (
      SELECT
          a1.N 
      FROM
          L1 a1 
          CROSS JOIN L1 a2 
      ),
      L3 (
          N 
      ) AS (
      SELECT TOP ((ABS(CASE WHEN @pStartValue < @pEndValue
                           THEN @pEndValue
                           ELSE @pStartValue
                       END - 
                       CASE WHEN @pStartValue < @pEndValue
                           THEN @pStartValue
                           ELSE @pEndValue
                       END))/ABS(@pIncrement)+ 1)
          a1.N 
      FROM
          L2 a1 
          CROSS JOIN L2 a2 
      ),
      Tally (
          N 
      ) AS (
      SELECT
          row_number() OVER (ORDER BY a1.N)
      FROM
          L3 a1 
      )
      SELECT
          ((N - 1) * @pIncrement) + @pStartValue AS N 
      FROM
          Tally 
  );
 GO

http://itdeveloperzone.blogspot.in/2012/11/generate-list-of-dates-in-sql-server.html