Bea WebLogic Server
J2EE Certified Application Server and JSP Engine
Blazix Java Application Server
Supports latest JSP release. Full application server features, including servlets, EJB, clustering, and JMS.
GNUJSP
Free implementation of Sun's Java Server Pages. [Open Source, GPL]
PolyJsp
An extensible JSP implementation designed to support multiple scripting languages and multiple JSP versions. [Open Source]
Resin
Java based XSL focused on dynamic server pages. This Java servlet supports JavaScript and JavaServer Pages (JSP). It also compiles JavaScript templates into Java byte code. [Commercial]
The Jakarta Project
An Apache working group dedicated to providing a high quality, world class 100% Java Servlet and JavaServer Pages implementation. Involves members of the current Apache Jserv Project and engineers from Sun, IBM, and other major corporations. Stable releases are now available. [Open Source, BSD-like]