I am glad this thread has been "expanded" to include passive defense measures. Pretty good link, Rap.

A few quick thoughts...
Peep holes in exterior and safe room doors.
I prefer dusk-to-dawn lights over motion sensor lights because we have trees here and, around this time of year, they fall and we also have a few cats, etc, around. Also, good lighting deters crooks BEFORE they get close.

A "No Soliciting" sign often prevents crooks, excepting the Jeezely Hovahs, from coming to the door for "casing the place". I never open the door for anyone I don't know. I look out the window and just shake my head "no".

I had a beware of dog sign on my garage and I have a large pet door repleat with a piece of 2" 100 grade chain attached to the garage that goes into the "door". I used to have the same type chain attached to the iron step railing at the front steps which ran to a hook mounted beside the door. I took the sign down because delivery peeps wouldn't come to the back door and the front door is often inaccessible in winter. The chain in front looked crappy.

I have a camcorder on a tripod pointed at the front room windows (I like to have them open in summer) and it's hooked to a VCR and the VCR has a coax cable running to a wall outlet. The light on the garage makes this visible at night.

Oh, yeah, almost forgot... I snore louder than a grizzly bear in a shock film.