nginx - A high performance free open source web server powering busiest sites on the Internet.
Apache HTTP Server - Apache httpd has been the most popular web server on the Internet since April 1996
Microsoft IIS - Internet Information Services is a web server for Microsoft Windows
Cherokee - High-performance web server
Apache Tomcat - An open source software implementation of the Java Servlet and JavaServer Pages technologies
WEBrick - WEBrick is a Ruby library providing simple HTTP web server services.