Cellphone.

Go shopping and buy something.
Ride on a train or airplane.
Surf internet.
Watch TV.
Download music or games.
Chat using messenger.

Of course I'm talking about cellphone.
There are so many services available (tempting).

So far, the latest service added on cellphones I know is "credit card".
There was already a service of "prepaid card", which can be used at convenience stores, train or airplane tickets, etc.
It just had a critical weakness, that "it requires to charge money first", while credit card doesn't require, it just charges directly to a bank account.

But the service I like most are camera and dictionary.
Furthermore, most of the computers don't have camera, do yours have!? ^_^

I don't want to pay extra money, when I can keep them cheaper.
I pay fix price to an internet provider every month, so why use cellphone to surf, download or chat?
Watching TV doesn't cost money, but it consumes battery quickly.

Nevertheless, primary use of cellphone is to CALL.
Mail or SMS could follow, but are the other functions necessary?
Answer may depend on everybody, but at least I don't need them.

I can't deny that "simple phones" are good sellers, especially for matured people.
Cellphone companies supply where there are demands.

Oh, I forgot to mention about the service "number portability".
Even when people change cellphone companies, they'll still have the same number for their SIM card.
This service will begin from this coming November.

Just be careful not to lose your cellphone!
It's a treasure box of personal information.