The Power of Behavioural Ads in social networking websites such as Facebook, myspace, twittr, and jaiku.
(Facebook adds that they wont sell any data, or share it. WSJ)

There are 6 potential layers of creative data intelligence that can make online advertising more useful to online consumers.

1. Contextual data: What content is the advertising next to? (environmental contextual ads)
2. Demographic data: Who is viewing the advertising? (IP lookup, browser language)
3. Behavioral data: What websites has the user visited and what ads has he clicked on recently? (during last minutes, hours, days)
4. Consumer choice: What types of advertisements has the user explicitly expressed interest in? (time spent, action made)
5. Relationship data: What do we know about the user’s friends that can enable us to better target the advertising? (msn messenger, connectivity,chat, emails history)
6. Collaborative/predictive filtering: What does multivariable regression analysis of the targeting data available tell us that the consumer may want to view? (example after checking his bank account, here goes loan ads)