A tutorial article from java.sun.com with the source code for a working minimalist webserver.

A small and fast http server with Servlet 2.3, JSP 1.2 support and full automatic recompile. [Freeware]

Includes installation guide, FAQ, bug list, and source.

Fully-featured web server with Java Servlet API 2.2 and Java Server Pages 1.1 implementation. [Shareware]

A HTTP Server and Servlet container written in 100% Java. [Open source, Artistic-like License]

The official W3C Java-based Web server. (W3C is the WWW standards body.) With a modular architecture and full HTTP/1.1 compliance, the Jigsaw server is an experimental platform for W3C and the Internet community.[Open Source]

A fast, conditionally compliant HTTP/1.1 server and Servlet 2.2 container specifically designed for embedded Java devices, including TINI, JStik, SNAP, and EJC.

Java server for Windows 9x/NT and Mac. [Freeware, requires registration]

A web server written in Java. Supports CGI, PHP, and Perl. Requires Unix-like OS. [Open source, GPL]

A secured Web Server developped in Java, Servlet container and using XT (a Java XSLT processor) to transform Xml into Html documents. [Open Source]