A brace of magic security cameras. After three years of deliberation (the old alarm was stripped out of the Asbestos Palace when it was refurbished). I don't like alarms, I figure all they're good for is disturbing the neighbours. Unless you pony up for the full security detail, I don't expect the police will rush around, and anyway, any practised burglar will be long gone before anyone turns up. There's the old alarm box outside and it looks like the sort of house that would have an alarm, plus there are lights on timers etc. A brief stroll around after dark makes it obvious which houses are empty. I'd make a great burglar. Hmm.
Anyway, we both travel a lot, and often out late in the evenings, the street lights go off at midnight and thereafter it's completely black, so it would be reassuring to know to house is still standing and if something does happen we might at least have some evidence. Though if the police treat any video the same as they do bike cams, I might not get my hopes up.
OK, I confess, it's mostly so I can spy on the cats and capture evidence of their many nefarious misdeeds. I tried to learn the psychic art of remote viewing and failed, so this is the next best thing.