Ever wanted to write something like this in SQL Server:
SELECT PRODUCT(MYCOLUMN) FROM MYTABLE
Well, wish no more:
DECLARE @P FLOAT
SET @P = 1
SELECT @P = @P * MYCOLUMN FROM MYTABLE
... provided you can use the query in a context that permits T-SQL that is (e.g. not in a view or a subquery). Note that you can perform arbitrary aggregations using this technique (say, summing while respecting null contagion, concatenating strings... the mind boggles).