I've got 10 years of JVM development, 5 years in Erlang, and I've dabbled in lots of other languages over the years, including Lisp, Prolog, Io, Javascript, Ruby, ML, Scala, Groovy, and Clojure. I think ML is super clean and elegant, and Lisp is the king of languages. I'm solidly a backend developer focused on system integration and scalability, not a user interface/experience guy.