Can you tell about them for all those non-US citizens?
Who are they and what are they doing? Pirating movies from torrents and going like "YARRrr" ?
Nothing that drastic...
but they are for copyright and patent law reforms. Or as wikipedia puts it:
Pirate parties support civil rights, direct democracy and participation in government, reform of copyright and patent law, free sharing of knowledge (open content), information privacy, transparency, freedom of information and network neutrality.
Also, there are Pirate Parties in several dozens of countries, a couple with official positions already. So, depending on where you are from, you might already have one near you:
http://en.wikipedia.org/wiki/File:Global_atlas_of_identified_Pirate_Parties.svg.