Honduras tried (is trying?) a libertarian city in special development regions. The article I remember reading is actually from December 2011; I didn't think it was that long ago and I haven't read anything new. Here's the article that might be a good starting point for you though:

http://www.economist.com/node/21541391

And here's an article on seasteading (basically huge platforms/ships that sit in international waters) from around the same time:

http://www.economist.com/node/21540395