Here's one I use to create a file name out of a DATEPART extraction:
"\\\\server\\Shared\\dir\\IS\\BI\\LastOrderFiles\\" + "LastOrder" + (DT_WSTR, 2) (DATEPART( "mi", GETDATE() ) ) + ".xml"
The "DATEPART" returns the minute (as an int) and I convert it using the (DT_WSTR, 2).
I do this in an expression srtting a package variable.
Hope this helps.
Dan