[vmelkon]

I was searching for stuff. I think I typed "liquid nitrogen" as my search term and came into this
http://www.youtube.com/watch?v=14B8LynojI4&NR=1

and also his website.
Apparently, some company has invented a reverse sterling engine. By running it, it removes heat from one side, enough to liquefy nitrogen. That guy found one on ebay for 300$.