I am using a "Plug Computer" (DreamPlug) to provide the physical I/O that the iPad lacks. It has 2 x USB, 2 x Ethernet, 1 x SD, 1 x eSATA & WiFi.
I can connect to it via WiFi using the iSSH and then use either Shell commands or XWindows (xfce) to copy photos from an SSD card to USB HDD etc while traveling. I also hope to get FileBrowser to connect to it so that I cam view photos stored on the HDD etc.
All the above requires some Linux knowledge. Hopefully there will soon be devices marketed to make this sort of thing pre-packaged.
The Acer tablet has an optional keyboard with built in physical I/O for example.
A GoFlex Satellite with USB ports & SD card slot and either XWindows exposed or a file manager app would be useful.