Google has applied for patents on technology that would allow the company to build psychological profiles of online users. 

The profiles would initially target users involved with online role-playing games like Second Life or World of Warcraft and would help advertisers target messages to individuals.
Any online user, regardless of what kind of device they are using – for instance: PC, PlayStation, Nintendo or xBox, could be monitored.
The company has filed patent applications in Europe and the US.
It hasn't made any announcements about using the technology.