This came up a few days ago on HN. There is brand awareness as well as direct sales. So if you see a Heroku advert, then see an article on HN a few days later a

This came up a few days ago on HN. There is brand awareness as well as direct sales. So if you see a Heroku advert, then see an article on HN a few days later about it, when looking for quick app deployment you may start at heroku instead of engineyard. Also, everyone underestimates how much advertising works. People often downplay advertising and beleive it affects others much more than themselves. While for low hanging fruit like MacKeeper, a shit-tier virus-spam-app that constantly is displayed via popups, targeted ads based on your preferences are subtle and difficult to weigh.