I can think of a number of things that the world needs that don't seem to exist yet. How about you?
Right off the bat -
A flash drive that allows the user to snap apart the USB controller from the memory. Thus if the controller blows out, you can resurrect the data by plugging in another one. I've lost two flash drives to controller failures so far.
A shoe sole that can maintain traction on ice and on hard floors. Right now it seems to be one or the other.