NGINX is a web server which is increasingly used. In november 2011, it was used by more than 11% of web servers analysed by Netcraft. NGINX is the 3rd web server used, just behind Apache and Microsoft IIS and far ahead of Lighttpd.
NGINX is used on high traffic websites like the Russian search engines Rambler and Yandex, the blogs platform Wordpress, Wikipedia encyclopedia or the SourceForge.net projects hosting. The NGINX web server is also used to host websites created by the 02Graphics Web Agency.
It has been proved numerous times that Apache is much heavier than NGINX to serve webpages. Apache uses much more RAM and CPU than NGINX.
It is well established that Lighttpd isn't stable when, among others, used with FastCGI. So, if you want to keep your websites online, it's probably better to use NGINX than Lighttpd.
Moreover, NGINX is easily installable on the FreeBSD OS with a simple pkg install nginx
and is easily configurable.
Besides stability and lightness of NGINX, it handles easily: