On Sat, 5 Sep 2009 10:44:16 -0700 (PDT),
wrote:

A third possibility is to replace the switch by a motion (sorry)
detector as used for security lights.

A PIR is a good solution. I had one in the kitchen of my old flat as
I'd be for ever leaving the lights on (3 x 100W spots) and
forgetting. Has the advantage that the light comes on automagically
when you enter and if it does switch off you just wave to switch it
back on.

An inital thought was a micro switch operated by the door, closed =
off. But that isn't very convenient when the room is in use. I don't
think a two way switching arrangement would solve that either.

--
Cheers
Dave.