Just found it on F.A.T., a Firefox plugin called google-alarm! Look at this tool and recognize how much information you expose by simple surfing.

To make it work on my Iceweasel 3.5.11 I had to change the em:minVersion in the install.rdf of the .xpi archive. It’s just for noticing, I don’t provide this changed version because you should not download such things from sites like mine ;)

You should also take a look at F.A.T., they often have smart projects!