Tracking urban migration trends?<p>The temptation that none of the big data hoover companies (Google, Microsoft, Apple, Facebook, Yahoo, etc.) will be able to resist is something else:<p>When you have so much data on everybody, you have created yourself a situation that allows you to "hack the system" to your advantage and the disadvantage of those who don't have all that data. You can analyze the trends that the data shows and link them to the movements of the stock exchange, and you're all set for infinite passive income and domination - now you know before everybody else what to buy and what to sell and when (you can call it "insider trading based on data").<p>Now, if you, as the user want to supply all that data, that's up to you. If so, you'll not only be appreciated by those companies but by certain government agencies as well.