Nginx ("engine x") is a high-performance HTTP and reverse proxy server, as well as an IMAP/POP3/SMTP proxy server. Nginx was developed by Igor Sysoev for Russia's second most visited Rambler.ru site, where it has been running for more than two and a half years. Igor releases the source code under a BSD-like license. Although still in beta, Nginx is already known for its stability, rich feature set, sample configuration files, and low system resource consumption.
Nginx can be compiled and run on most Unix like OS, and there is a Windows ported version.
NetCraft reported in June 2008 that more than 2 million sites have used nginx to provide services, surpassing lighttpd.
From:
http://www.nginx.cn/ 
