Problem is, without some incredible funding, no third party candidate is going to look any better than Nader.
A third party candidate will look good when some issue that enough people really and truly care about shows up. Honestly, as much as I'd love to see a third party based off of the likes of Jesse Ventura, I think the most likely third party at this point will be made up of the religious right, after they break with the GOP. If GWB was unable, unwilling or whatever to get them the power/votes/laws/amendments that they wanted... it should now be obvious to them that the GOP has no plans to push their agenda, except during election time for votes.
This really has the potential to scare the crap out of me. Religion has a pretty good handle on human psychology. Religious leaders have charisma, they can whip a crowd into a frenzy and hold that sort of attention regularly. If shit looks really bad, people want religion (cause it gives them someone to blame). Consider, for example, the free market, wild party land once known as Venice. The Venetians, during the Enlightenment, basically kicked the Church in the face and pulled most of their power. However, once the plague showed up, they all turned back to the Church for salvation. If things get bad here... I could totally see something like this happening. Remember, most Americans still consider themselves Christian....
Think about how well Huckabee did. If he had been on a third party ticket, that would have been enough votes for the debates to have been Obama, McCain, Huckabee. Now, if a lot of Baby Boomers felt threatened by Civil Unions, by Evolution in Schools, by secularization... how many Americans could be scared into voting Huckabee? How many 'moderate' Christians might have thought it was ok, because he was a nice Pastor?
As for the independents (of which I am one), most seem more than willing to decry partisan and two-party, but they are not usually fanatics. Many don't appear to hold strong beliefs on exactly HOW things should go. Sadly, as bad as belief and fanaticism may be for the brain of any given human, it also seems like a major driver for any political party.