I've seen some cool stuff,one of which called "road star" which is basically a chain with spikes every few inches.Used to stop light-wheeled vehicles,the same item that was used in the film "HEAT"
http://gear4privacy.com/Defense/selfdefense.html
there's some other cool stuff,like the "booby trap alarm" which fired a blank shell when tripped.Anyone know of any good products/sites where perimeter/home defence items like this can be found,and if you have any experience with them?
thanx

i sometimes see surplus razor wire on ebay.

American Survival Guide magazine used to have advertisments for surplus US GI seismic perimeter alarms. If I remember correctly they were remote sensors you put around your perimeter with I think a 100 yard range. Always sounded cool in the ads.

The best home perimiter defense, IMO, is a pair of large aggressive dogs (I prefer Rotts). Helps to have some land and live way out in the country though.