At this point, it would be highly irresponsible of me to point out that this months Superbike magazine (Feb 0
has a feature about people who've taken their garage security to extreme levels - apparantly it is possible to "enhance" the alarm mines with pea gravel, and that a combination of those, a photographers flash gun or a strobe light and some suitable sirens can disturb potential thieves sense of balance significantly.
Theres a good example of this operated by a guy in Reading, so I'd steer clear of his place uninvited - 12Hz strobe, 2 alarm horns @ 127dB and a 128dB siren, plus a fog machine and CCTV to watch the burglar suffering on.