The largest impediment to effective action on climate change is lack of political will. As such, I find the approach of the Citizens Climate Lobby group to be rather encouraging. Their focus is on getting people across North America to contact their political representatives directly, eventually reaching the point of meeting them in person. The organizers argue, rather convincingly, that such an approach is likely to have much more of an effect on the thinking of legislators that just sending letters or (even worse) emails would.
In an ideal situation, CCL members are able to distinguish themselves as useful sources of impartial information about climate change, who can be relied upon by their representatives in that way.
So far, CCL is largely an American initiative, but there are three chapters already in development in Canada. Those who are interested in getting some training and participating in the effort should have a look at their website and consider participating in one of their frequent introductory conference calls.