Just an idea. Many have a spare N900. Some carry their around, for some it could be fun to turn theirs into active being. Scenario:

You come home in the evening, welcomes you bright light already on, turned on by movement of the door (simple to implement I believe), once movement stops in the corridor and has moved to the guest room, lights go out there (tricky part is turning them back on time for wandering toilet seekers) Routines for all kinds of typical activity can be built. Question: does N900 camera suffice for depth analysis? Are two needed to fake a Kinect? Can we plug Kinect to the N900 (or can we find a talented enough person to reverse engineer the driver?) and use its HW?