To be honest, I think your country is more likely to implode before it drags itself out of the two-party system. That is not meant to be a slate against the US - it's just that I really can't see how a country, so dependant on an antagonistic and diametric form of democracy, can ever begin to consider a genuine
"third way" (I shudder when I use that term... it was Blair's phrase back in '97).
Culturally speaking, the US seems to revel in polarised and extremist debate - or at least, this is how things appear at a national level from the outsider perspective. There's a lot of frankly nasty bullshit spoken about the US and its sometimes difficult to get an accurate representation of US culture - especially one so diverse in a country so large. But to me, there appears to be a mindest of 'us and them' ingrained within US political culture - a mindset that permeates both internal and external US debates/policy, and is ultimately appealing in it's simplicity to mass media outlets that fuel debate.
Britain fares only a little better. We have three 'main' parties (with the usual compendium of greens, independants and fascists on the fringe) who tend to continually act like children, telling sneaky lies about the other parties, arguing with eachother and successfully avoiding coming close to a reasonable solution. Our media still plays the simplistic 'bounce one off the other' routine, but usually manages to do it with a greater degree of objectivity and lesser aggression (and without the sinister manipulation) than what I've viewed of US TV news.
Put simply, even if it was achievable, a third party won't necessarily solve the problem of aloof, cruddy politicians.
On a final note, you do actually have a
third option.