One interesting use of Lua is in LaTeX. Recent distributions of LaTeX come with binaries luatex and lualatex. I'm not familiar with the exact details, but if yo

One interesting use of Lua is in LaTeX. Recent distributions of LaTeX come with binaries luatex and lualatex. I'm not familiar with the exact details, but if you'll Google around you'll find many references to LaTeX internals being rewritten in Lua. I've found LuaLaTeX to be quite stable already and used it to compile my PhD thesis.