Seth Godin pointed to a study from the AOL Global Advertising Strategy about who actually clicks on ads:

'Advertising is the bread and butter of the web, yet most of my friends claim that they never click on ads, typically using a peacock tone that signals their pride in being ad-averse. The geekier amongst them go out of their way to run Mozilla scripts to scrape ads away, bemoaning the presence of consumer culture. Yet, companies increasingly rely on ad revenue to turn a profit'

'Who are these "heavy clickers"? They are predominantly female, indexing at a rate almost double the male population. They are older. They are predominantly Midwesterners, with some concentrations in Mid-Atlantic States and in New England. What kinds of content do they like to view when they are on the Web? Not surprisingly, they look at sweepstakes far more than any other kind of content. Yes, these are the same people that tend to open direct mail and love to talk to telemarketers.'

http://sethgodin.typepad.com/seths_blog/2007/12/your-ads-are...

http://www.zephoria.org/thoughts/archives/2007/12/03/who_cli...