I've ran Kontera for a couple of years and they were great. And then they simply stopped earning any money. Looked like they lost some anchor advertiser or something. These smaller ad companies (basically anyone other than Google) go from boom to bust in a matter of one month, easily. Always have to watch them.
Anyhow, I do still run Infolinks. They are a-OK, nothing to write home about. But I do suppress in-text ads until the parts of the page where no AdSense can appear. So, it's basically unused real estate anyway.