For Christmas this year I bought my friends a 5/2 programmable thermostat, so that they wouldn't be heating their home during the time they're at work. Later I even installed it for them. I got it for them under the auspices of saving $$$ since their heating bills in their recently-purchased home were a lot higher than their former townhome's bills. But also it saves a little more oil from being burned, a little more CO2 from being thrown up into the air for no reason.
Now if I can get him to put in some insulation, instead of just talking about it...
Have you ever considered buying one for someone you know? Or have you done it? It's a great way to help people take that green step even if they're only doing it to save $$$.
The one I bought, by the way, was a Honeywell model with a "weekday" and "weekend" setting (5/2).