Unite the left? A more informal option

Dana at the Galloping Beaver lays down the gauntlet to NDP supporters here. I understand the concern with stopping Harper, but I already know that the NDP retort will be something along the lines of "Liberal, Tory, same old story." In other words I don't see it happening.

I live in a fairly NDP riding, one where the only real competition will provided by the Liberal party - so we here Trinity-Spadina can't really do much more than we are already doing to stop Harper. Vote splitting here is a moot point.

As of right now I don't hold a membership in any political party - and unless one of the parties somehow does something spectacular I don't imagine that that will change. I suspect that there are more than a few people in the same position. We vote progressive, but we aren't beholden to a particular party. What I'm proposing is that we look at polls and aim to support the progressive candidate most able to beat the Harperite option.

Now since we don't have proportional representation in this country, there's not much difference that I can make where I am, but for people in swing ridings, this kind of consideration might make a difference. I know that this was tried in the 1990s with Mike Harris without too much success, but with the advent of the blogosphere the ability to share this information is greatly increased.

What do you say? Can we compile a guide for the best Harperite defeater in every riding?