You can tie the filehandle to a class that adds any amount of behind-the-scenes functionality to the basic filehandle. To the rest of your script, the filehandle would look and behave pretty much like a regular filehandle, but behind the scenes all sorts of stuff can be going on. perltie has info on how to do this, and you can also read more at Tie::Handle.

This sort of approach isn't for the faint of heart, so be sure to get yourself in good physical and mental shape before trying these stunts. *wink*