You might remember some previous messages on the topic:
<http://lists.wikimedia.org/pipermail/wikiquote-l/2010-October/000118.html>
<http://lists.wikimedia.org/pipermail/wikiquote-l/2010-September/000111.html>
A few days ago, as a test, I fetched the ISBNs on fr.quote and en.quote
and created some accounts/lists of their books.
For instance: <http://www.goodreads.com/frwikiquote> and
<http://www.goodreads.com/enwikiquote> allow us to have some easy fun
with stats on quoted books.
From en.quote's perspective, compared to French:
Wikiquote francophone > Compare Books
Wikiquote's books: 2575 (1795 not in common)
Books in common: 780 (31.19% of your library and 30.29% of their library)
My books: 2501 (1721 not in common)
And to Italian:
Wikiquote > Compare Books
Wikiquote's books: 7403 (4938 not in common)
Books in common: 2465 (98.56% of your library and 33.30% of their library)
My books: 2501 (36 not in common)
From Italian to French:
Wikiquote francophone > Compare Books
Wikiquote's books: 2575 (1700 not in common)
Books in common: 875 (11.82% of your library and 33.98% of their library)
My books: 7403 (6528 not in common)
Italian seems to quote all the books that English does, plus many more;
a third of fr.quote's books are quoted also on en and it.
Sadly, for some reason fr and en have a very little amount of ISBNs in
their pages, while I expected fr to be very complete (given how many
citation templates they use) and of course en to have more stuff given
that they have more pages (perhaps they're not about books but something
else, I don't know).
German and Polish had a negligible amount of ISBNs, I didn't check the
others.
I think more publicity of Wikiquote could be done on those booklovers'
portals, but I can hardly manage the Italian accounts and adding more
good quality data is time consuming. I've offered the accounts to the
communities, if nobody wants to take care of them I'll delete them:
<https://fr.wikiquote.org/wiki/Wikiquote:Le_Salon/d%C3%A9cembre_2012#aNobii_and_GoodReads>
<https://en.wikiquote.org/w/index.php?title=Wikiquote:Village_pump&oldid=1515928#GoodReads>
Nemo