This is why Twitter is so great. I might not have discovered this for ages without Twitter.
On Bite-Size Edits, editors and readers (that is, anyone who visits the site and is interested) are given three consecutive sentences and allowed to edit and leave notes for the second sentence. The sentences all come from texts submitted by members (and anyone can join for free).
Although the process is billed as a game -- you get points for making edits and suggestions, plus more points when your edits are deemed useful, and high point earners can win FREE BOOKS -- this is really an odd and quite enjoyable way to crowdsource the editing process. If nothing else, it can be a good way to exercise your editing chops.
Although this likely won't lead to a well-polished book, Bite-Size Edits can be of great use to striving writers, if only emotionally. Once you've submitted some text, it can feel good to know that work is still being done on your writings even if you have an off-day when you don't write. If you do start to get some good suggestions, it can also encourage you to keep writing so you'll have something new to post and keep the process going. Plus, there's the automatic (and, yes, egotistical) joy of knowing that you actually have an audience.
The site is still in beta, so there may be some bugs to fix and improvements to come. I don't know yet how well it can handle text formatting, for example. But it sounds interesting, and it really is quite fun.
So fun, in fact, that I've submitted one essay that I wrote (and sold!) a few years ago. You can read the original essay here, and if you like, start editing it one random sentence at a time here, though I suggest you you go to the Bite-Size Edits home page and edit the random sentences that it pulls from random submissions.
A warning, though: This is highly addictive. Plan on accidentally spending twice as much time as I think you'll spend there.