What Toy Apps would you write in order to learn a language?

Let's say I wanted to learn Lisp, Haskell, Scala, Clojure, Javascript and Ruby. What set of toy applications would I have to write in order to say I have a good feel for the capabilities of the language and largely understand it?

For example maybe: Quicksort, Directory structure read/store/search, ping pong game?

I would guess that this question might be too general and should be broken down into sub sections, what do you think?