I agree with peter12. I don't have an idea off the top of my head of a better way to do something like this, but for the hell of it, I'll give an example of a symbolic gesture that actually makes a difference.
Anybody ever do that 30 Hour Famine back in the day? I used to (have) to do it every year. We'd go around knocking on doors for sponsorship and then have to go without food for an entire day. It was usually a big sleepover with the church youth group or with schoolmates.
After you were done, you'd collect all the sponsorship money that (assumably) goes and buys food for starving people.
I don't want to debate whether the people at World Vision are on the up and up or whether there are religious undertones involved. Just saying that that sort of symbolic gesture has results that get felt.
The concept of earth hour is as useless as those stupid gas boycotts that circle around email inboxes from time to time. The idea is that everyone is supposed to refrain from buying gas on the same day in protest of gas prices.
Brilliant. If I don't buy gas today, I'm going to buy it tomorrow, in a greater amount.

So turning off your electricity and furnace and everything for an hour is only going to result in a spike in usage the next hour. It's as stupid as Kyoto.