Imagine that you decided to try to make some money on your web site by running some ads.
So, you go to a page where ads are available to be chosen, and used, and you pick out three or four that are appropriate to your site.
You check to make sure that your site is appropriate for the uses envisioned by the advertiser, and if it is, you cut and paste the code for those ads into a text editing program, and then into the template for your blog, or the html for your static web site.
The ad runs until the owner's cash reserve is emptied - then the ad disappears.
This is more work than something offered by some text-ad programs, but owners of sites get to choose the ads that run on their sites. There's a lot of value to that.
Will we ever see this model of advertising? I hope so. It's described in more detail on John Battelle's Searchblog: Sell Side Advertising: A New Model?
There's a lot of value to being able to choose your business partners. It's always possible to find them on your own, but not really easy. Unfortunately, most systems for showing ads are accompanied by adhesion contracts where the large company supplying the ads have all the power, and all of the say, and the people displaying the ads have no ability to negotiate.
I've had troubles with automated, contextual ads from one of the large online booksellers showing products from competitors. (Fortunately, you could choose which books to display from them rather than just use the contextual system.) I'd once signed up with a large reseller of hosting and domain services to act as an affiliate, only to get so disgusted by their practices that I yanked all links to them, and never contacted them ever again.
It would be great if someone set up an advertising clearinghouse where people could select the ads they wanted to show quickly and easily.