I tried that for years. The green vote really never grew. Then I switch to the GOP.
The PPC in Canada got enough votes this time to be able to get reimbursed for campaign expenses, and I think they get some other advantages for future elections. None of the other parties were offering any alternative to what's happening up there. Once people finally get pushed too far, they will have an alternative to turn to.
I switched to the Libertarian Party after the Patriot Act was voted in. Then the LP turned its back on actual Libertarianism and started advocating for more government intrusion into people's personal affairs. I'm still registered LP, but I never voted party lines. I would vote for a democrat, if they weren't all hopelessly corrupt. If I'm unsure, and there's a constitution party candidate, I'll err towards him or her.