99 Bottles of Beer is a really fun (for a geek) website that has a huge collection of programs written in different programming languages, that all print the lyrics to "99 Bottles of Beer." It is a great way to show off the basic elements of a language, such as conditionals, loops, variables, string printing, etc.
There are examples of language simplicity, such as this Python version. Or the complete absurdity of a language, like the Perl example the looks like ASCII art of bottles of beer, but is actually executable Perl. Then there are the crazy funny languages like lolcode and COW.
If you are using Mac OS X you can use Homebrew to install CoffeeScript and Node.js (required for command-line CoffeeScript).