Very nice, I've been looking for something like this that actually works and isn't trivial. I got some really nice results.
First (nitpick point): You've got a misspelling in the page: scarse instead of "scarce" underneath the bars that show frequency.
The UI on the right is a bit confusing and busy. I suggest removing all the text around each of the options. I might then put them at the top of the screen with the "go" button. Move the descriptive text to a little popup (more info/?/help/whatever) link next to each of the options and shove all the text in there. Something like:
Languagae (more info): []English []Spanish []French []Italian
is going to be nice and clean.
My gut feeling is that most people are not going to read the text right away and they are just going to play with it and see what happens. This is why I suggest a clean UI so they can easily play, and give them ways to discover what the options do. You don't want to put speed bumps in front of users and force them to comprehend everything out of the gate.
Another usability point: I got stuck once I typed a pattern in. I tried to delete the pattern (to go back to random mode), but the site kept using the pattern. I then realized that instead of deleting the pattern, I had to change the dropdown menu to be "Create random wordroids". This leaves the text in the pattern box but does revert to the random setting. I would re-work this with some ajax or something so that it's not so confusing.