I'm thinking about voting Libertarian also (or possibly one of the other 3rd party candidates). I don't feel there is any significant difference between the two major candidates. Both want to spend (and tax) way too much. I tend to vote republican because they are supposed to be the party of small government, low taxes, not trying to police the world and so on. However, the Republican party hasn't been coming through on these issues in a long time. I don't want to vote Democrat because it seems they are becoming more and more socialist all the time and quite frankly, I really don't like the idea of the federal government trying to be my mommy and daddy.
I know that there is no 3rd party candidate that has a chance of winning, but if enough people vote 3rd party, it will send a message and possibly pave the way for a 3rd party candidate to win in the future. To me, having the first non-democrat, non-republican president (in a long, long time anyway) is far more important than having the 1st woman, 1st black or any other 1st I can think of for president.
Both candidates claim they are the candidate of change but really neither one is. As long as people think of a vote for a 3rd party candidate as a wasted vote and as long as they instead vote for the lesser of two evils, I doubt there will be any significant positive change.