The way i saw that they were doing to get members to there site was a trick, Ofcourse there site will have changning content all the time on the pictures members upload and the comments they leave. But another thing was that they used alot of rss feed's and alot of articles. If you look closely on where it says MAKEMONEY on that site in the navigation. That is where they are getting alot of rankings from is just by having that in there site

I am wanting to create several sites just like that site under small niches and see how much traffic i can generate