Shelly has a good essay here: Clouds and Pirates: Darknets Rising | MediaBytes with Shelly Palmer.
"At the end of the day, P2P networks and strange or alien files are not going to cause any more economic hardship for the content industry than they are causing right now. However, good natured, good citizens using private storage clouds are going to be hugely hurtful. And, if good citizens can cause irreparable harm by paving the road to hell, imagine what bad natured, bad citizens will be able to accomplish with the same technology. Trust me, the computer network does not know the nature of its users..."
His list of virtual drop-boxes and sharing sites is useful, as well: