This web app based on Spring provides flashcards. I use them to study Portuguese. Initially, you are presented with english. Click on it and you will see the Portuguese. Clearly this could be extended to other languages should one desire.
This app uses open source code and some icons from open clipart (http://openclipart.org/) under create commons. To run it, you'll need jQuery, jQuery UI, and 'Flip!', a jquery plugin (http://lab.smashup.it/flip/).