Perhaps "what are you searching for?" Messages posted and available to read through that interface will be to and from your Google Contacts. (That's the people you Gmail with, basically.) Google is making a big push for people to take their Google Profiles more seriously and one consequence of that could be a well populated social graph for users.
Friends could help answer the questions you're asking of Google or they could let you know what they are doing, like a home town version of Google News.
Test Pilot is sort of a distributed usability lab. It uses simple crowdsourcing mechanisms to gather data from volunteers all over the world as they interact with web apps and desktop software. The collected data remains transparent and openly available, so the data sets can be used by anyone.