[smartera]

(I work in market research industry for promotions/ad optimization and effectiveness; off and on-line)

I agree completely with Maciej points. There is one other factor that should be considered; the more ads served to us (normal consumers); the less our reception to them is thus the new ads need to be more powerful. Only giant companies can fund the creativity and subtlety needed for very effective ads on a large consumer scale; everything else is noise in the consumer mind except for tiny well-targeted niches. Those are the two groups (giant companies and very niche businesses) that will survive the consumer-ad bubble burst easiest.