Brian Holtz has posted a list of the top 30 Libertarian blogs. I've copied it here for ease of reference on my part more than anything else. Hit the link to see his ranking criteria. It's a combination of traffic and inbound Technorati links. All commentary below is his.
Glenn Reynolds: Instapundit - "The Blogfather" is a liberventionist who ignores the LP as "trivial" and "a net negative"
Raimondo & Garris: antiwar.com 2 Rothbardians have flitted among 4 parties, backing Buchanan 2000 & Nader 2004
Andrew Sullivan: The Daily Dish Time hired the gay Catholic New Republic ex-editor who coined "South Park Republican"
Lew Rockwell Culturally conservative anarcho-capitalist paleolibertarians who disdain the LP
Reason 60K-circulation techno-optimistic libertarian magazine bemused by the LP
Neil Boortz The libertarian-leaning conservative talk radio personality
Volokh Conspiracy Law school profs who say the LP makes major parties less libertarian at the margin
Marginal Revolution Brilliant GMU economists/philosophers/aesthetes ignore the LP
Homeland Stupidity A libertarian look at technology and privacy
Hammer of Truth Most important LP-friendly blog; Stephen Gordon is now LP Comm Director
Jane Galt: Asymmetrical Information Libertarianish economics-literate journalism; McArdle hired away by The Economist
Daniel Drezner Tufts PoliSci prof gets 58/160 on the libertarian purity test
Radley Balko: The Agitator Cato Institute policy analyst says "the LP is bad for libertarianism"
Vodkapundit Liberventionist who criticizes "doctrinaire libertarianism"
Samizdata Broad US/UK/Australian perspective from liberventionists who call the LP "turgid"
Jon Henke et al: QandO Interventionist neolibertarian Republicans who have given up on the LP
Strike the Root "A libertarian / market anarchist perspective" that says the LP isn't radical enough
EconLog 2 brilliant economists, including anarcho-capitalist theorist Bryan Caplan
Becker-Posner Blog Chicago's economics Nobel laureate and brilliant federal appellate judge
Catallarchy Founding liberventionist Brian Doss says the LP's job is to discipline the GOP
Virginia Postrel: Dynamist Former Reason editor, NY Times columnist, and Future And Its Enemies author
Cato At Liberty Official Cato Institute blog
Cafe Hayek 2 more brilliant GMU economists who focus on ideas, not politics
Vox Populi "the Christian Libertarian commentator from WorldNetDaily"
Technology Liberation Front Libertarian perspectives on technology
Rational Review Tom Knapp's web journal seeks a radical LP for this "revolutionary era"
Cato Unbound Monthly big-idea essay and reaction essays by big thinkers
Positive Liberty Intelligent libertarians embarrassed by the LP's anarchist silliness
Kn@ppster ZAPsolutist anarchist Knapp is hedging his LP bet with a new protest party
Coyote Blog Capitalist libertarian thinks the LP is too kooky
Will Wilkinson: Fly Bottle Ex-GMU Cato Institute policy analyst
Free Liberal "non-partisan left-libertarian journal of politics and economics"
David Friedman: Ideas Milton Friedman's son is the world's leading utilitarian anarcho-capitalist theorist
He's also done a list of the top 13 Libertarian websites:
Ludwig von Mises Institute The leading American institute for Austrian economics
Cato Institute Arguably the most important force for freedom since its 1983 schism with the LP
Libertarian Party The only American political party advocating personal and economic liberty
Library of Economics and Liberty No bricks or mortar, but a potent academic-oriented web presence
Future of Freedom Foundation Advocates the "free markets and limited government that made our nation great"
Advocates For Self-Government Pushes its Nolan Chart quiz and lists libertarian celebrities
Ayn Rand Institute Official institute for Rand's Objectivist philosophy
Independent Institute Second only to Cato as a libertarian think tank; GMU's Tabarrok directs research
Reason Foundation Libertarian think tank specializing in privatization, environment, and California
Adam Smith Institute
Institute for Humane Studies Founded 1961, moved from Menlo Park to GMU in 1985, focuses on scholarships
International Society For Individual Liberty Students for Individual Liberty (1969) merged with Libertarian International in 1989
Downsize DC The late Harry Browne's group for petitioning Washington