SELECT [Month] = DATENAME(mm, DATEADD(mm, MONTH(SomeDateTime), 0)),
         Amount  = SUM(SomeAmount)   
 FROM #MyHead  
 WHERE SomeDateTime >= '2010' AND SomeDateTime < '2011'  
 GROUP BY MONTH(SomeDateTime)  
 ORDER BY MONTH(SomeDateTime)

-- This builds a table with random dates and amounts for 20 years 
-- starting in the year 2000.
 SELECT TOP (1000000) 
     SomeDateTime = RAND(CHECKSUM(NEWID()))*7305 + CAST('2005' AS DATETIME),

 SELECT [Month] = DATENAME(mm,SomeDateTime),
        Amount  = SUM(SomeAmount)
   FROM #MyHead
  WHERE SomeDateTime >= '2010' AND SomeDateTime < '2011'
  GROUP BY DATENAME(mm,SomeDateTime), MONTH(SomeDateTime)
  ORDER BY MONTH(SomeDateTime)
;

select datename(M,convert(varchar,months)+'/01/2010') as days
from (select 1 as months union
select 2 as months union
select 3 as months union
select 4 as months union
select 5 as months union
select 6 as months union
select 7 as months union
select 8 as months union
select 9 as months union
select 10 as months union
select 11 as months union
select 12 as months ) as M
order by convert(datetime,convert(varchar,months)+'/01/2010')

 SELECT [Month] = DATENAME(mm,SomeDateTime),Year(Somedatetime),
        Amount  = SUM(SomeAmount)
   FROM #MyHead
  GROUP BY DATENAME(mm,SomeDateTime),Year(Somedatetime)
  ORDER BY CAST(DATENAME(mm,SomeDateTime) + ' 1900' AS DATETIME),Year(Somedatetime)