...i.e., download all data in some sort of readable format like CSV or plain text, and maybe to the computer or to GDocs or Dropbox?
There is no way to backup by the ease of a button at the moment. I am working on making it easier for other developers to write applications around weekplan, so someone could decide to write a backup tool.
I am adding your suggestion in my todo list, but it is fairly low priority in my todo list so please don't expect it in the next months as I am flat out.
Customer support service by UserEcho