The Movimiento Libertario is a very interesting political party (Spanish website, English version is here). It is just about the only avowedly-libertarian political party in the world with significant clout in a national assembly. They regularly return a number of deputies to Congress, and have been instrumental in voting down a number of nasty illiberal and expensive laws. I don't know why Libertarian politics should have found a home here, since in many ways the political system here is still old-fashioned paternalist socialist.
Contact me: d a g g i l l i e s @ y a h o o . c o m