I like seeing more and more software extensible by Lua, which is a very decent language. My very favorite is LuaTeX (luatex.org), where you can access all ugly TeX internals from Lua and even create a complete typesetting system without using the rather complicated TeX language, which is based on macro expansion. I am not so sure if I'd use Lua Bash, for bash has always been "good enough" for me.