How To Launch Your Site on a New Ubuntu 12.04 Server with LAMP, SFTP, and DNS
How To Install WordPress, Nginx, PHP, and Varnish on Ubuntu 12.04
How To Install WordPress with nginx on Ubuntu 12.04
https://www.digitalocean.com/community/articles/how-to-install-wordpress-with-nginx-on-ubuntu-12-04
Extra
http://timwhitlock.info/blog/2010/08/varnish-with-php-and-wordpress/