As part of my day job, I've been doing a lot of research into the ever and quickly expanding capabilties of USB drives to act as portable computers (minus a screen, keyboard and connectivity of course). I've looked at U3, Ceedo, PortableApps and mojopac.
Of those 4 (which ones am I missing? Please let me know), U3, Ceedo and PortableApps result in a similar end state. The main difference being that Ceedo and U3 both require software on the USB to run associated apps - PortableApps does not require any additional software to be downloaded or installed to the USB drive in addition to the applications. mojopac works differently in that it actually creates a a whole new virtual PC on your USB drive.
We are still researching all the implications of these various packages but I remain amazed at our ability to install and run everything from Moodle to Skype to OpenOffice all from these USB devices with little or no difficulty.