I did not try this but there is a backup function from/to USB (user manual page 412). This only seems to allow copying a selected folder, not single files. But knowing this beforehand might make this handable...
If you want more control and are familiar with linux and linux command line: as D-Links other DNS NAS, the 327L supports unsupported extensions (

) via user defined fun_plug scripts. With ffp 0.7 there's great package available which I successfully installed, e.g. to enable an SSH server. But, as said, beyond D-Link's basic support to install such scripts I think there is no further support provided in this forum. There are nice tutorials on the web, especially on http://nas-tweaks.net/.