Funny the list doesnt mention casino.co.uk – maybe the list is US only
They claim to receive 3,000,000 visitors a month with 10,000,000 pageviews.
They charge a flat fee of £2.50 ($4.60) per click on any of there ads around the site
so even with a 10% click rate per visitor = £750,000 ($1,400,000) Per Month