Michelle Kessler & Byron Acohido:

When customers sign up for a free Hotmail e-mail account from Microsoft, they’re required to submit their name, age, gender and ZIP code.

But that’s not all the software giant knows about them.

Microsoft takes notice of what time of day they access their inboxes. And it goes to the trouble of finding out how much money folks in their neighborhood earn.

Why? It knows a florist will pay a premium to have a coupon for roses reach males 30-40, earning good wages, who check their e-mail during lunch hour on Valentine’s Day.

Microsoft is one of many companies collecting and aggregating data in new ways so sophisticated that many customers may not even realize they’re being watched.