As technology moves on, we're getting closer and closer to the time where money as we know it could get abolished, and those dozen cards we carry around in our wallet could be simply gotten rid of.
The technology for an electronic economy, and the replacement of cards already exists and is in very widespread use; the RFID chips used to chip pets contains a serial number which, when entered into a given database, will pull up medical and contact information.
The way I see it, this technology is prime for exploitation in humans too, think about it, if you had a chip implanted in your wrist, the things that the infrastructure is 99% already in place to do;
No more keys; many office buildings already use RFID cards for access control. With a system like this in the home too, you just register your chip with the unit and you'll never need to carry a key again.
No more cash or cards; My new card has an RFID chip embedded in it. At certain places I can wave it across a payment machine and presto, I've paid for stuff. On a small, easily lost card I hate this idea, but for a chip embedded in your wrist? Much harder to lose.
Public transport; In London, the Oyster card lets you take public transport all day without handing over a penny. Swipe the card over the pad and you're done; this is, again, RFID.
No need for ID; Driving licence, passport, proof of age, and a multitude of clubs and other IDs. Lose them and with a wave of your wrist, people will get a nice easy true or false confirmation as to whether you are allowed somewhere.
Medical care; Some people wear bracelets to alert medics to allergies or previous problems. This system is already in use for pets, where you scan them and up pops all the animal's medical data. Why not do the same for humans and make life easier for everyone?
I'm a staunch supporter of bioenhancement through technology, so if this were offered, I'd be first in line, but would you do it?