I have many sites that need articles written for them. If you can write original content, you can put a single adsense ad in the post (the sites mostly only have 1 of my ads in the sidebar). I also have a new site which has very easy updates. You just post the latest viral videos or images that you see, and write a little bit about it, like "In this viral video, a guy almost gets hit by a car but just escapes!" etc. If you are interested in this, let me know via PM, and I will make you a contributor so you can make posts. In the posts you can just put your adsense ads.
It sounds like he's just looking for free content in the hopes that his rankings will skyrocket. EDIT: I didn't even notice the signature. I'm actually going to guess that he's just building up free content to his site and he's going to try to sell it on a Flipping site. Also, you can only display a limited number of AdSense codes simultaneously. The main reason I don't do these "residual income" opportunities is because in my experience, the owners of these sites usually abandon them a month in. I've seen it far too often, the owner gets frustrated a little in that they're not making great money and then they say screw it.
As the title says, the trade is that they write content to put their ad. The writers and I both add content and share any rewards that come of it. Also, in the main site I'm looking for, as I said in the post, it's hardly tough work, it's just posting relevant videos and writing a couple of lines of text to describe the video, so it's an easy way for someone to get their adsense or backlink out there. I know, you can only have 3 on any page, that's why there's only 1 ad on the site from me, so the writers can put their own safely. Edit: I'm also looking for opportunities to do this myself, so if anyone in this thread has a site they need good content for, and are willing to let the writer place an adsense ad in their page or a backlink, let me know the site!