If you are not a privacy-conscious individual and wish to help Google know what an average user's online experience is like, then read on. The thing in question is called Google's Screenwise panel, which is currently full, unfortunately; but there is a chance Google might let more people in at any time, so you should be checking the Project's page quite frequently.
What's the catch and how it works?
Well, for the initial approved sign-up you will be getting an Amazon gift card for 5 US Dollars; in return you will have to install a plug-in for your Chrome browser that will collect and send the usage data to Google's servers. Of course, this means you have to be a Google Services' user – that is, have a Google account of some sort. Every three months you will be rewarded for your volunteer participation. There is a second, a more lucrative, option, however. You have to install the Screenwise Data Collector hardware on your network for which you will get paid $100 initially and 20 dollars for each month you participate. Not bad.
Where do I sign up, so I can Help Make Google Better?
Just visit SCREENWISEPANEL page from time to time to see if Google has opened up more spots for those who are willing to participate. Finally, note that you have to be at least 13 years of age to participate. Best of luck!