AutoChron 3-pack Wireless Wall Switch Timer- $50 shipped at COSTCO.com (+ $2.50 non-member fee)
Amazon has these $30.98 EACH, so $92.94 for 3 vs $52.49, as they charged me a $2.50 non-member fee.
These easily pay themselves off quickly if you forget to run your exterior lights. I have 3 light switches in my house, even though I use CFLs, we are talking 100watts between the 5 exterior lights I run...and they are at $0.12/kw, so by turning them off 14hours a day I save 44kw each month or 528kw/year, so $63/year.
Plus, they sell used for $20+ used EACH on ebay, so if you get rid of them, its all good.
Granted, you dont need this if you remember to turn on your outdoor lighting off during the day, which I dont, and this was the cheapest solution I found to do so to control 3 light switches.
If you live in the inner city, or the ghetto, I've found having a well lit exterior keeps the crackheads away.