I first learned about Koans from EdgeCase Ruby Koans project, it was great fun and great practice. Since then, whenever I mentored a DevChix or RailsMentors member I suggest to start doing Koans… even on a regular basis, once you finish them all … then start over! I always have a ruby koan mid-way and work on it when I want to practice ruby. Sometimes I try to complete the whole file then run it. Since I’ve been learning Groovy this week, I looked to see if there was Groovy Koans, found those.. then I just started compiling all the languages I know of..

Ruby

http://www.rubykoans.com

Python

https://github.com/gregmalcolm/python_koans

Groovy

https://github.com/cjudd/groovy_koans

Javascript

https://github.com/mrdavidlaing/javascript-koans

https://github.com/liammclennan/JavaScript-Koans

Java

https://github.com/matyb/java-koans

Scala

https://github.com/rubbish/scala-koans

Erlang

https://github.com/patrickgombert/erlang-koans

Perl

Sadly…I was not able to find one for Perl …

Functional Koans

FSharp, clojure, haskell, python, scala

Functional Koans

Lua

Lua Missions (based on koans)

Java

JavaKoans

CoffeeScript

https://github.com/sleepyfox/coffeescript-koans

And while I was searching for other languages… I ran into this

http://rosettacode.org/wiki/Main_Page

Its has sample problems done in multiple languages. Kinda fun!! (I recognize some of them as interview questions)