I've looked at the lua/nginx integration a while ago, an all the examples struck me as somewhat confusing. A lot of work was done using lua as inline nginx configuration (or just normal nginx config). Mongrel2's Tir[1] looked a lot cleaner and better documented.

[1]: http://tir.mongrel2.org/

and also https://github.com/ezmobius/super-nginx, an even bigger Swiss Army knife.