from the other direction, it looks like haxe [http://haxe.org] is planning on adding a java target. fantom [http://fantom.org] already does both java and js too. it's a pretty well-filled ecological niche.
also, if you like single-language stacks, give opa [http://opalang.org] a serious look. it's essentially based on ml, with a javascript skin, and offers strong static typing and easy integration of front-end and back-end code.
I'm glad you brought Opa up. I saw it a while ago and thought it was interesting, until I saw the license it used (AGPL).
Thankfully, your comment made me seek it out again and I saw they also added MIT for the framework part, so that apps can be licensed in any language. Will have to try it out now that they have given users that choice.
Besides those, there's ceylon, gosu, Xtend, probably some others, for JVM. My impression from the forum is that kotlin is not quite settled but I haven't written any code.
One reason why I chose Node.js over Scala for my current personal projects is that I prefer programming in the same language on the client and server.
That being said I've never used Kotlin and can't compare it with Scala, which I have used for my personal and commercial projects.