This is about a month old.
Actually, scrap that. This kind of thing never gets old.
To wit, a presentation on implementing and "using" Fractran, via clojure of course.
The least silly aspects of the show are (1) that we can implement the language very concisely and functionaly, and (2) to interpret the results, there's a nifty sieve of Eratosthenes - the real one.
The code is on github.