Hi,
As far as I can see, the Collection extension, which provides the Special:Book page, is deployed on nearly all Wikimedia wikis.
Is there data that shows how often do people actually use it?
-- Amir Elisha Aharoni · אָמִיר אֱלִישָׁע אַהֲרוֹנִי http://aharoni.wordpress.com “We're living in pieces, I want to live in peace.” – T. Moore