So far it's just a couple status LEDs (door open/closed and a "doorbell") and sketchy wires but I'm planning on cleaning it up once I have time.
All the resistor values are completely arbitrary, I grabbed them at random and they work. If I thought it through I could probably get the LEDs a little brighter but it doesn't matter too much. The only important things are that the resistors are large enough so the LEDs don't burn out and R2 has to be small enough to pull enough of the current so the LED doesn't turn on.
Bare wires, when you short them together the red LED turns on. I'm planning on putting a nicer button here
Aluminum tape on the door and weather stripping (convenient for sealing a door and guaranteeing good contact!) with wires duct taped on each contact, since only the non-sticky side of aluminum tape is conductive.
All of it together:
EDIT: As several people have pointed out, it would be smarter to do the door switch with a transistor. The reason I didn't was because the circuit got about a minute of thought (if that) and I just grabbed a few parts near me.