New York magazine has a long article out, "The Trouble With Liberty," which surveys the modern libertarian movement. It has some criticisms, but I thought the article generally did a pretty good job.
The author, Christopher Beam, explains where libertarians become illuminated to their brand of politics: "Ayn Rand has been called the “gateway drug” to libertarianism, but many converts keep toking well into adulthood. Her novels, including 1943’s The Fountainhead and 1957’s Atlas Shrugged, sell more than 800,000 copies a year. Other libertarians credit their conversion to Hayek, fellow Austrian economist Ludwig von Mises (Ron Paul’s personal fave), American free-marketer Milton Friedman, or Austrian-influenced American anarcho-capitalist and father of modern libertarianism Murray Rothbard."
Those suggestions all seem useful, but when I went to college in the 1970s and discovered my political identity as (more or less) something called a "libertarian," ILLUMINATUS! had a bigger effect on me than anything else.
I'm guessing the book influenced other folks' political thoughts, too. Dan Clore, in his list of "Essential Science Fiction and Fantasy for Libertarians," writes that "Robert Anton Wilson probably ranks as the quintessential libertarian science fiction writer."