A recent article in The Columbus Dispatch talks about why Americans should support third parties. Here's an excerpt:

Article II of the Constitution states that if no presidential candidate receives a majority of votes, the House is to select the winner "from the five highest on the list." No one in 1787 envisioned presidential elections with only two candidates. The Framers figured that lots of people would run

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The title of the article highlights a great distinction - support vs. vote for. As you read to the end of the article it is clear that he is not saying you necessarily have to vote for them but having them run is important to our Democracy. Hearing their voices is important to our Democracy. We all can do our part for the country, even if we plan on voting for a major party.

I found this article through a great site that watches the world of ~~third parties~~ non Republican & non Democrats. The simply call themselves Third Party watch.