By now, many of my friends have moved on to points in their lives where they have to pay for their own expenses. For my friends who have to pay their own utility bills [or if they leave the light on as long as they are awake (even if not in the room)], I like to get them compact fluorescent light bulbs. In a way, I'm forcing my agenda on them and they like it. That's right, they'll be saving energy. Also, they're saving money. I think it's a sweet setup and everybody wins.
I've tried to do this with canvas bags before. The problem is that people forget to use them or don't like the color or something. With the lights, you screw it in and it works just like any other light & there's no more effort involved. I call that "incentive compatibility."