Tea Party -- The invention of Fox News and some wealthy donors, as inspired by the Rick Santelli rant on CNBC, as a temporary re-branding of the GOP so that all the Republicans who woke up on 1/20/09 and decided that deficits are bad could have an unspoiled label to give to their anti-tax beliefs. This was a very effective movement for its intended purpose: the 2010 elections. It had some downside, in that it wasn't 100% controllable, and ended up costing the GOP senate seats from Delaware and Nevada along with some other elections.
Libertarianism (small L) -- A wide range of socio-economic-political belief systems focusing on minimizing the role of government so as to maximize market efficiency and individual freedom. Many of the usual cranks and crackpots have taken up the libertarian banner to advance their cause. Even really famous libertarians, like Ron Paul, are only selectively libertarian.