SSIS Data Types
This is a useful guide on MSDN for mapping SSIS Data Types to that of various databases.
http://msdn.microsoft.com/en-us/library/ms141036.aspx
The top part is an explanation of each SSIS data type. Further down is a mapping of various databases (notably SQL Server, Oracle and DB2) data types to SSIS types.
Brian Knight has a nice grid mapping SSIS Types to SQL Server which is a little easier to read for those working in a pure SQL Server environment.