Very small embeddable Java web server. Run Servlets compatible with Sun's Java Web Server.
BEJY - Bebbo's Java Server
BEJY is a modular server application, designed for small memory footprints and high performance, written in Java and supporting HTTP (JSP, servlets), SMTP, POP3, IMAP.
Creates and maintains open source solutions on the Java platform for distribution to the public.
Javasoft's Web Server, written in Java
Full blown HTTP server entirely written in Java