I think that the 'tired' old parties, as you claim them are actually the smart vote. Independents don't win unless both Republican and Democrat candidates are horrible. John Kerry and George W. Bush aren't the best candidates, but if we were to have someone like Joe Biden and uh... George H.W. Bush Sr., then we would have a match. Then would be the time for a strong independent/third party candidate. Otherwise, if Hillary Clinton or Arnold S. (I doubt it...) would run as an independent or third-party candidate, we might see them win. Look at this....
In 1912 Theodore Roosevelt ran as a Third-Party against his friend, and now rival William H. Taft (the incumbent Republican), and Woodrow Wilson. Most Republicans voted for Roosevelt, but some voted for Taft spliting the Republican vote, and gaining Wilson the electoral vote and more. Roosevelt won almost 100 electoral votes, and Taft only had a few, surprising the country. That was the biggest example of an almost-successful independent campaign.