I've been working on a mud using Clojure and my friend who's helping with the management side was asking about finding other coders to help. Which got me wondering, are there any other Clojure programmers out there in the mudding world? How about other JVM language muds? I saw someone with using Groovy, Maybe Scalas out there too?

Honestly hadn't heard of it until today but after looking it over it seems like a neat language. I might have to put it to use at some point.

There are many Java MUDs out there and as you said there are some Groovy things happening (although I only know of one guy here). I don't know of any Scala MUDs nor had I heard of other Clojure MUDs before now.

RingMUD is (being) written in Java/Python/AspectJ/XQuery, with its core being Java/AspectJ. flumpy is making GroovyMUD in Groovy. CoffeeMUD is a stable Java MUD codebase. WolfMUD (where I originally learned the base concepts required for RingMUD) is written in Java.

Those are the only ones I know of.

I've switched to using the Jruby implementation of Ruby. It's not a JVM language per se, but it's a JVM implementation that's quite nice from the perspective of a Ruby developer. It really shores up some of the problems with Ruby for some applications while delivering the full Ruby lexicon. It features using java from ruby. Using ruby from java. True concurrency with no GIL. JIT and AOT compilation. Which is nice because it allows you to ship Ruby applications without requiring the typical Ruby implementations being installed. Java is much more common to be available and more friendly to embed. Furthermore, it doesn't require you to expose your code the way publishing with ruby2exe would. Additionally, the fine tuned java environment is quite a boon. In any event, I'm of the opinion that Jruby is currently the best implementation with yarv and Rubinius close behind for general development.

edit: Oh, and a really neat project to look at is Mirah. I'm very excited to see how it progresses.