The best description I've ever heard is that they are Republicans who want to smoke pot. Most of the Libs I've run into personally are uninformed people who read "The Fountainhead" in college and were too naive or dense to realize that all Rand ever produced was a bunch of tendentious bullshit.
Libs think everything will be all hunky-dory if everybody does their thing and nothing is regulated; the "marketplace" will take care of itself. But it won't. There is no such thing as a free market; government *of necessity* controls the rules of the market -- and there would be no market without government. Without a structure -- that is, a regulatory framework and a court system to enforce it -- the market simply cannot function.
And Libs are all fine with the "I've got mine; to hell with you" philosophy until they need something from that awful ol' government. Hurt on the job? Where's my workers' comp money? Lost their job? Where's my unemployment compensation? House on fire, car got stolen? Fire department and police better be there right damn now.
I have no use for Libertarians; they have no clue about much of anything. And Ron Paul can go screw himself. By the way, Paul is intellectually dishonest even for a lib; he's against government regulation of mostly everything except abortion. But the government has to stop women from exercising their right to reproductive freedom.
Best (and funniest, ever) summary of Randianism here:
http://www.democraticunderground.com/discuss/duboard.php?az=show_topic&forum=389&topic_id=1481845