Hopefully this post won't be relegated to the Accessories discussion because I think that it is relevant in the General Discussion area.
I have always been disappointed by the inability of the iPad to be used for simple tasks such as copying photos from an SD card to a portable HDD and will admit to have become obsessed about finding a solution.
Well I think that I have found one, a "plug computer".
These are minimalist, portable, low power consumption Linux boxes typically with WiFi, USB ports and even an SD card slot. Mine also has an eSATA port.
For those who don't want to tinker with Linux, FileBrowser can be used to view and copy files on/between USB drives and SD cards. These devices seem to automatically create SMB shares thus making USB drives and SD cards available in FileBrowser.
Copying files through the iPad (via WiFi) can be a bit slow and FileBrowser has limited file filtering and wild card options.
A more techie solution is to connect to the box using iSSH and make use of Linux file commands or Perl scripts. Scripts have the obvious advantage of being able automtically take care of a complete file copying and housekeeping routine. The advantages of this over FikeBroswer include speed (I would guess 5 times faster) and automation of routine tasks.
Of course I would much prefer this to be available on the iPad itself.