In this month's Business 2.0, Susanna Hamner profiles Fetchback, a three-month old online advertising start-up. Fetchback's niche is "retargeting" which means that it follows visitors to your site after they leave and shows them a sequence of your ads as they browse other web sites with the hope that each incremental exposure, and potentially more enticing offer, will ultimately get them to click on your ad. Hamner notes that retargeting isn't new and that "online ad giants like Blue Lithium, DoubleClick, and Right Media have experimented with it in recent months. " Try for 9 years. DoubleClick launched its Boomerang service 9 years ago that did exactly the same thing. I know because when I was at i33 communications we tested it out for Sprint which was a client at the time. I'm amazed at how much the cast of characters in online advertising technology has changed in the last 9 years yet the technology has remained largely the same.