[s3r3nity]

Yeah but CPM (cost per impression metric) is not a scalable business model alone -- CPC (cost per click) or CPA (cost per acquisition) metrics have arisen because sites will spam impressions to people in Malaysia who will never buy anything...cheap impressions don't power a site for very long unfortunately.

[ceejayoz]

Many sites in the news media are still primarily on impression-based ad revenue. Often, a print advertising purchase comes with a certain number of impressions on the website.