Strawberry is a great tool that checks folders for incoming files. It will repair and unpack the files for you. It currently supports Par2, Split, Zip, and Rar files. When used in combination with your peer-2-peer client, newsreader software or other download client Strawberry will automatically repair and unpack incoming files for you.
||Free to try
||Windows 98/Me/2000/XP/2003 Server/Vista