User tracking seems to be far more valuable than ads. I'm currently subcontracting for a specific large media trust. Ad contracts are in total about 6 figure numbers. User tracking, sponsored content and skins (custom stylesheets with a sponsor's branding and tracking) are very substantial 7 or 8 digit contracts.

While it's true his own activity isn't worth much, it's still a piece of a very lucrative pie. There are services already oriented specifically around user tracking.

I guess they're oing by the principle of individual behavior is unpredictable, but mass behavior is.