I've signed a lot of local hippie do-gooder petitions in my day, and joined a lot of mailing lists. Today I received a link to a website that makes voting suggestions on a riding-by-riding basis, showing the most strategic way to defeat the conservative candidate in each area.
Vote For Environment
The thinking behind this site is that any party would be better on environmental issues than Stephen Harper and the Conservative Party of Canada. I've been ashamed of Canada's stance on environmental issues since Harper came to power, and am still angry about his international betrayal of the Kyoto Protocol, so I certainly agree that a vote against Harper is a vote for the environment. I'll be happy if this website helps anyone make a difficult choice between several appealing opposition candidates, as we have in my riding.