You know what would be very convenient? If the door to your home had an RFID card reader so that it could be programmed to let in anyone with a particular card. You could give houseguests a few days worth of access, without having to worry about getting keys back from them.
Because it would be web-connected, you could authorize people to have access to your home remotely. You could even have an option for unlocking the door through a web interface – for instance, in order to let a repairperson into your place.
There would need to be good security all along the line, from the radio communication between the RFID cards and the reader to the communication between the door control system and you via the web. Rather than try to achieve that though proprietary means, it would be better to publish all the hardware plans and software code and let people spot weaknesses that could then be fixed.
This seems like the sort of thing that will invented one day. One one hand, it would be convenient, while on the other, I’m not sure I’d want to deal with my door getting hacked into, in more ways than one, or crashing and having to be re-booted when I just want to go inside and use the washroom.