QUOTE
So, it looks like Wikia's page views per user's usage day is about 3/8ths that of YouTube, and about 1/5th that of Facebook.
Alexa also informs that about 33% of visitors to Wikia.com leave immediately after looking once at the arrival page (the "bounce rate"). Compare Wikipedia Review.com at about 46%. Facebook, 12%. YouTube, 21%. YouPorn, 8%.
Consider though that most people who go to Facebook or YouPorn know exactly why they are going there. What's the bounce rate for other major wikis or specialized encyclopedias?