Draft, at Draftin.com, is an online writing tool that focuses on a writers progression through several drafts of a writing project, keeping track of each one as the writer moves along.
A simple email and password are required to join. The site offers very limited formatting options so the writing focus is on the content, not the look. In fact, you have the choice of a couple of fonts and sizes, and that is it. There is no underline, no boldface, no italic, no color, no images, no fonts. Just writing. Even the logo is very simple.
The process could go something like this. You start out by typing your first rough draft. Come back a day later and make changes. Then a few days later make additional changes for a second revision.
Finally, you send it off to a peer for their input. They provide their revision, however, you have the ability to accept which ever revisions you'd like, from just 1 to all the suggested revisions.
At anytime you can review any of the prior revisions of the document, and even revert back. All revisions are maintained for reference. Here is an example of a document I revised, revised again, and had peer reviewed.
You can export your document to a variety of online services like Google Drive, Drop Box, or Evernote. Once exported, any further revisions done in draft can be synced to the exported document.
This tool offers great possibilities for young writers learning the draft revise process of perfecting a piece their writing. In fact, it's fairly good for those of you that are more advanced.