I saw some very interesting research from Forrester today about the growth of online advertising. They feel that the growth of direct response advertising like PPC will at some stage be outpaced by brand advertising, banners and so on, online.
Look at it this way, of my sites my cocktail recipes site has a smaller level of traffic than my paper airplanes site but the cocktail recipes traffic is predominantly adults in the 18-35 bracket which is definitely of more value to banner advertisers.
Users unknowingly tell webmasters and ad networks a lot about themselves. Operating system, referring domain, browser and version, JavaScript enabled. I am positive that someone who elects to use firefox is telling you something meaningful about themselves.
Geotargetting is already huge at a country level and is the first step into more granular targeting of users. A typical way of monitoring offline ad performance is to have dark regions and light regions and then observing what happens in each region.
Google has made a move with CPM banners into their adsense network but I wonder if their brand has the elasticity to stretch beyond being a highly targeted direct response advertiser. There is a space here for someone else to really nail this… could it be Yahoo?