Nginx is a great little web server. I have posted previously about using it as a reverse proxy. Weather your using it as a reverse proxy or as a normal webserver you will probably eventually want to know what its doing over time so you can adjust resources as necessary.
The other day I threw together a Zenpack to make it easier to setup monitoring on new Zenoss instances. It contains a command data source “check_nginx_ng” which is a slightly modified version of Chris Kellys check_nginx_ng which in turn was based on check_nginx by Mike Adolphs. So thanks to them for doing the majority of the work! If your interested you can pick it up over on github. ZenPacks.community.NginxStatus