Thinking about the bits of data you leave behind is a one-way ticket to paranoia.
Your browser? Full of cookies. Your cellphone?
A beacon broadcasting your location at every moment. Search engines track your every curiosity. Email services archive way too much.
Those are just the obvious places we're aware of. Who knows what's going on inside those routers?
The truth is, worrying about the trail of digital footprints and digital dustballs filled with our digital DNA is not just for raving paranoids.
Sure, some leaks like the subtle variations in power consumed by our computers are only exploitable by teams of geniuses with big budgets, but many of the simpler ones are already being abused by identity thieves, blackmail artists, spammers, or worse.