External Hard Drive With Pda

I am trying to find out if there are any PDA's that will allow you to read/write etc. to an external hard drive without going through a computer.  I take a lot of digital photos and don't really like carrying a laptop when I travel.  I have a 100 GB external with USB interface.  What I would like to do is take the SAD card from my camera, put it in the PDA and copy the files to the external hard drive.  Anyone ever try something like this?

Thanks,