For serving a lot of static content from a single processor machine, few apps beat
LightTPD. This web server is designed to have very low resource requirements and to be fast. It can generally handle about twice as many requests as Apache for static content. For dynamic content, it supports CGI and FastCGI. FastCGI eliminates the process creation and destruction overhead of CGI by allowing a single process to handle all requests for a CGI script. The FastCGI interface is supported by PHP, allowing LightTPD to serve PHP pages at least as well as Apache.
When scalability is king,
Yaws (Yet Another Web Server) is often a good choice. It’s written in
Erlang, a language designed for concurrency, and scales very well. The entire system is designed as a number of concurrent processes, allowing for very high throughput.
Got that, from
http://www.informit.com/articles/article.asp?p=472693&seqNum=2&rl=1