As I was working outside today as it got dark, I saw the glow from the light in my backyard. We have been in our house over 2 and a half years, and have left the backyard light on all of that time. And yes even during daylight. That is because our backyard light is a CF bulb.
From the folks who bring you Wikis, social networking, RSS and zombies in plain English(Common Craft). I give you compact fluorescent bulbs in plain English.