For quite a while, you've been able to get security lights with timers that automatically come on at night and go off, to make burglars think you're home when you're really not. And you can also get programmable timers, so that the lights go on and off at times of your choosing, not always at the same time every night (someone staking out your house while you're gone might become suspicious if your lights turn on every night at precisely 7:00 pm). But now, even more sophisticated security lights are available.
You can buy whole-house home automation systems that turn lights off and on automatically, different lights in different parts of your home (inside and out) at different times, all without you having to be there to do a thing. You can even integrate your lights so a microprocessor remembers your lighting habits for two weeks and replicates them when you leave for vacation.
Yup, lights on timers are a whole lot smarter these days. If you've got a dated system (or no automation whatsoever), it might be time for a security upgrade. And if you enjoy various aspects of home automation, you might even have fun planning it all out.
Lots of stores, online and off, sell the equipment to get you started, so just get out there and look around. There are also magazines on home automation that can be great resources. Just browse through Borders or another big book store with a large magazine section, and you'll have no trouble finding ideas.