The "Run Program" dialogue allows you specify a program or a batch file that you want uTorrent to execute when any torrents download completes, or on any number of events while you download or seed. Here is an example:

"d:\program files\utorrent\run-program.cmd" "%D" 

This will cause utorrent to run the "run-program.cmd" batch file wit the file-path as a parameter to it.

A full list of the possible events and parameters are available on this dialog.

Run Program