jgehrs:
I'm brand new to the Arduino world and want to tackle an interesting real life project. I want to create a wireless door unlock mechanism for my front door, just like unlocking your car as you walk up to it.
Unlocking doors electrically happens all the time; typically there is a solenoid that pulls the locking bolt. You can even buy electric door locks/jambs that have this built in.
However, the "sensing you approaching" part is much harder -- you will need a RFID system that can read from a distance, which will cost you a fair bit of money (a few hundred, most likely.)
Some alternatives include NFC, where I have no idea of the cost of the range, sender, and transmitter, and Bluetooth 4, where the "key" could be recharged pretty seldom, and the reader would use a rotating secret system to make it reasonably secure -- but latency of syncing up might be slow.