I'm not a libertarian and I don't agree with 75% of what they believe in -- but the Washington State Libertarian Party did something kind of cool. Reason magazine points out they're suing to get Mitt Romney off the ballot in Washington. The LP claims the state's Republican Party did not follow proper procedure and officially nominate a candidate for Senate in 2010. According to state law, that means the Republicans no longer count as a "major party" in Washington. That makes Romney a non-major candidate and the rules are different for non-majors. They have to follow a whole procedure involving collecting signatures and stuff. Romney did none of that, therefore he legally shouldn't be on the ballot.
I'm not familiar with that state's law or politics, but I know libertarians like to latch on to ultra-literal interpretations of the law and argue that anything not conforming to that interpretation is invalid. Those arguments usually get thrown out of court. Plus, even if their argument has some legs, I'm sure a judge who's a registered Republican will throw it out for whatever reason they came dream up - or the local Republicans will "convince" a judge to rule against them. Still, it may cause a few headaches for Mitt's boys. Hell, maybe we'll get really lucky and the LP will win their case. Either way, I say good on you, libertarians.