We can sit here and dicuss till we are Blue in our faces, Ron Paul or Bob Barr or any of the non mainstream candidates and at the end of our discussion, fact is they aint gonna win.
As Gun owners, and that is a big chunk of the people here in this forum, Obama is a horrid candate. Fact.
The reality though, is that your one vote isn't going to swing the election one way or another anyways. As such, I vote for who I think is the best candidate, even if I know they're going to lose, because it's the right thing to do. Because honestly, as long as everyone thinks "man these guys suck but we gotta vote for one or the other", the situation will NEVER change. There was a very comical Simpson's episode where two aliens wore Clinton and Bush suits, and at a debate came out out of the suits and declared that they were going to enslave humanity - and Ross Perot still lost the election against the two of them. That was a comical cartoon, but it had a lot of meaning behind it.
Will Bob Barr win this? Of course not. Even he knows that completely and fully. The Libertarian party is not naive enough to think that they have even a remote chance. The purpose in running though, is to TRY and get a respectable percentage of the votes. If they get 0.5% then they lose and people ignore them next time. If they get 5% though, then they lose and people start thinking next time that they might get a little closer if we all band together. It's iterative. Try and get a respectable number of votes enough times that the people too afraid to cast the vote that they really want will finally feel safe enough to do so.
And truthfully, I think that even if it's not my party of choice (Libertarians), we need SOME type of 3rd party alternative if only to break up the cold split there currently is in politics. Our country is absolutely a mess right now because of bipartisan politics. It's created one of the worst "us vs them" scenario's I've ever seen or heard of. Each group hating the other, each group thinking the entirety of the other are sheep blindly following their herders, and each telling the other side to get out if they don't like it. At least a "triangle" would keep the pointing going in multiple directions rather than the extreme polarization we have today.