Rovio is a “Webcam with wheels.” So, a camera that you can drive around in its space. It connects via wifi, and has a microphone so you can project your voice through it.
iRobot makes something similar (a “virtual visiting robot”), and the usage example they offer is grandparents “visiting” their grandchildrens’ home — driving the robot from room to room to visit the kids.
I think there would be a security angle too. If you were on vacation, you could drive the robot around the house once a day just to make sure everything was in order. My wife is always paranoid about some water leak wreaking havoc while we’re away, so this would let her make sure everything was dry.
But what do you do about stairs? Get one for every floor?
Rovio is $300.