The AA.com and Poker Charts banners have tracking codes on them. They could be affiliate links.
Another trick i’ve noticed some people doing lately is to make a informative site with no affiliate banners, get it placed in directories like DMOZ and Zeal as a non-commercial site. Once the site is in the directories the webmaster throws a few affiliate links up. The state that DMOZ is in it would take 6 months at least before they realise whats happening. By that time he’s in the google directory too, and been on top of the search results for having a few good links to his site.