For convenience, here is the comment thread:
Who will come to this site? How can it reach a critical mass of users that have read all the books that have errors? – Tadeusz A. Kadłubowski Jan 19 at 10:29
Some books have many simple errors that are nevertheless very confusing for students. If a class of people is using a textbook together, they can all use the site to vet probable errors with each other and get their TAs, professors, or even the book's author to weigh in. – Chinasaur Jan 19 at 10:46
The site will have words like "errors", "errata", and "textbook" in its main page and about page. Questions will be posed with the title of the book, ISBN, and authors. Tags will augment this information. I believe over time people will find the page via search results. If a few TAs or professors find the page and use it for their classes, growth with accelerate. – Chinasaur Jan 19 at 10:51
Some authors or publishers have already posted extensive errata for their books online. We could seed the site with general questions about errata for these books and answer the seed questions with links to the author's or publisher's official list. – Chinasaur Jan 19 at 10:52
I believe we can use the tagging infrastructure to organize errata - I think this will not work well. – Charles Stewart Jan 19 at 15:07
I know it's not ideal, but could you elaborate? – Chinasaur Jan 19 at 17:49
@Chi: Not all books, say, have just one ISBN. There are many significant internet-published works that don't have ISBNs or ISSNs at all. DOIs, as well as titles, can be longer than 25 characters, the SX maximum. With three tags used for author, UID, and title, there are only two tags left for thematic grouping. It's hard to get people to use tagging the way it is intended, even with simpler schemes than this, solving the above problems will make things harder. The software is tailored to Joel&Jeff's particular vision of Q&A, I don't see it working well to another vision. – Charles Stewart Jan 27 at 11:48
I think the proposal could be closed as "not a real proposal", but I would like to wait and see if Chinasaur has more thoughts.