I've had several close encounters with libertarians recently and I have to be honest with you, many of them piss me off as much as, if not more, than religious fundamentalists. There is a fairly popular libertarian niche today that is quite outspoken and very ideologically driven, and it seems to have a lot of young people in their ranks. There are also quite a few atheists who are libertarians and I've been noticing them as I go out into my local atheist/philosophical meetups.
Although I am sympathetic to some of the libertarian social views like marijuana and prostitution legalization, when it comes to economics and government I have some sharp disagreements with them. Many libertarians that I've spoken to either want no government at all, or government so small it can be drowned in a bathtub, to paraphrase Grover Norquist. But mostly, they want a total "free market" economy where government regulation is non-existent, and some even want the total privatization of education, law, police, and the military.
Not all libertarians hold to Ayn Rand's Objectivist philosophy, but many do. She's the ideological darling of many on the Right. Her fan boys include Wisconsin Congressman Paul Ryan, who said that her books are "required reading" for his interns. The interesting thing is that Ayn Rand was an outspoken atheist, and it's odd how so many on the Right identify with her, given the Right's close associations with religion. As far as her atheism is concerned, we're on the same page. We both see religion as something irrational and not justified by any good evidence. But Rand's philosophy emphasizes a kind of ethical egoism, whereby she thought that we should never sacrifice anything important to us for the benefit of someone else who was not important to us, like a stranger who was suffering. She thought taxation was theft, but still believed in government doing the three basics: police, law, and military. (This would be financed by voluntary donations according to her.) All the money you make would be yours to keep and there's no concern for any kind of "greater good." Rand's philosophy is a fervent objection to utilitarianism. If fact, recently when I mentioned my concern for the "greater good" when I was debating economics with a libertarian, he literally walked out on me.