There's also Lapis, a really great and reasonably feature-full web app framework for OpenResty: http://leafo.net/lapis/. I wrote a website in it recently and was pleasantly surprised at how cool it is. It reminds me a lot of Rails, but everything works faster, especially on LuaJIT, and I actually like MoonScript (the compile-to-Lua language I'm using) for its expresiveness and aesthetics. Definitely recommend checking it out.

We use the lua support in openresty to build our authentication layer for admin tools outside of those admin tools. Very easy to integrate it with a third party authentication platform and just provide auth for free to our app developers.