DropBox is an online document storage site. For free you can store up to 2 GB of data and access them from any internet based computer, or Iphone. The nice thing about DropBox is that once you install it onto your computer you simply drag and drop files and they become almost instantly uploaded. Much faster than Google Doc's. You can share and edit your files, see revision history just like Google Doc's. The only difference I see is the speed of upload.