I also agree this is a very powerful approach. If you'd like to see it in action already you should check out [OpenResty](http://openresty.org/). It's a platform for doing Lua directly on top of nginx. Each request can run Lua from within a coroutine, and and you can issue nginx subrequests which block Lua code but don't block the sever. See [ngx.location.capture](http://wiki.nginx.org/HttpLuaModule#ngx.location.capture) and [ngx.location.capture_multi](http://wiki.nginx.org/HttpLuaModule#ngx.location.capture_mul...) for issuing multiple in parallel.

nginx's subrequests can do just about anything with the right modules, from database queries to HTTP requests. Effectively turning nginx into your event loop. It's a very interesting idea.

I've just started using it, but I'm excited to make something with it.