Your cellphone is your front door key

Alright, you probably already don't like losing your cellphone, and it'll be even worse when your cellphone also doubles as your wallet, but pretty soon it might also double as your front door key. At least in Japan, where several companies are working together to adapt NTT DoCoMo's FeliCa wireless payment system so that you can also use your cellphone to lock and unlock doors (one bad thing: if there's a blackout, you better hope that the backup battery in the door doesn't run out). The "kesaka service" will also let you do stuff like check to make sure that your doors are locked from your handset (or even get an email every time it's unlocked) or issue duplicate keycards with expiration dates so your unwanted houseguests can get the message that it's time to go home.