Thought this might be a fun picture for you all. Here I am copying files between my N900 and a 250GB HD via USB, using equipment that is both lightweight and very portable. The worst part is the cables. I need to get shorter and less bulky ones. The hard drive obviously needs power injection in order to spin up. The N900, sadly, also needs power injection. It won't go into USB mode without enough power to start charging from USB. (I tested with just the N900 and N800, it wouldn't work without the batteries.)