There is this process that happens that is starting to gain popularity called, "Vote Pairing". It's not a new process, but people are starting to consider it more this year. Basically the way it works is for people to swap votes. For instance, if I live in California and it is projected that Kerry will win this state, and I team up with someone in another state where Nader is on the ballot and it is very likely that a vote for Nader will give Bush an advantage,... then I can swap votes with this person. In other words, since Cali is already going to win Kerry anyway, I will vote for Nader and my team-mate will vote for Kerry. That way in the swing state, a vote for Nader ends up being an advantage for Kerry.

This sounds good in theory. The legality of it is being questioned though.