How does this site below get such high google listings considering it has very low content not a great layout and design and Its filled with adsense banners. It must obviously be to do with the linking system? Is this correct?
Content actually means very little, content is just for the users benefit mostly because a 1 page website can gain top rankings for competitive terms if the linking strategy is spot on.
If you look at some of the back links you can see there are a number of homepage and sitewide links in place which is probably why it ranks well.