Did Nader really “pull” any votes (no matter how you define it) from the Dems? He didn’t get any electorial college votes, AFAIK, so the question is: In any states that the Dems lost, were the votes for Nader enough to have shifted the outcome in that state to the Dems? I know that in '04, if everyone who voted for the various third party candidates (Nader, Libertarian, Pat Buchanon, Nutjob Party, etc.) had voted for Kerry, he still would have lost TN. I have a feeling that it’s the same in most of the other states as well.
IMHO, voting for either the Republican or Democratic candidate in the general election is “throwing your vote away.” Your one vote isn’t going to be enough to shift the electorial college one way or another, and the major party candidates only care about the “big picture” as it were. A third party, however, will care about each individual vote they get, because the more votes they get (even if they don’t get an electorial college vote) will be more ammunition in their case that a third party can be viable in the US. (And yes, I realize that if everyone followed this logic, we’d wind up with a third party candidate in the White House, given that the immediate response to this by the two main parties would be to get their shit straight, I see this as only a positive. Besides, it’s not like a third party President would be able to do much of anything, anyway.)