There is an online advertising bubble (10+ years) that will be self correcting soon. The reasons are:

- Down economy. When ordinary people are going further and further into debt, they will differentiate products on price and not brand. They will cut back on all things save the necessities.

- Consumer startups are dying/getting smaller. Techcrunch recently mentioned venture funding drying up in consumer space, instead the money is flowing more towards enterprise. Therefore, those startups won't have massive budget to advertise online anymore.

- Big corporations will be scaling back on paid advertising. They can use free platforms like facebook pages and twitter to do the new product rollouts and announcements, which is becoming more of the norm.